If you're shopping for a computer now, there's an added factor to consider. Later this year, both of the major computer operating systems, Microsoft's Windows Vista and Apple's Mac OS X Leopard, will be replaced with major new versions: Windows 7 and Mac OS X Snow Leopard. And that affects what PC hardware you should choose.

    So, in this annual spring computer buyer's guide, I'll pay particular attention to buying a machine for the new OS you may soon want.

    This guide covers both laptops and desktops and is aimed at average users doing typical tasks. It doesn't apply to hard-core gamers or video, audio or photo professionals.

    Cost: Prices on Windows PCs have plummeted. You can buy a Windows desktop for under $300, without a monitor, and a low-end, full-size Windows laptop for around $500. If you are willing to settle for a so-called netbook -- essentially just a small, cheap laptop running the aging Windows XP operating system -- you can get a decent one for $350, or less. Even Apple, which has resisted this cut-rate trend, is offering modestly lower prices or higher specs for the same prices as before.

    Timing: Despite the bargains, you may want to wait to buy, if you can, until the new operating systems emerge. That's because it's usually easier and cheaper to buy a new machine preloaded with a new OS. You don't have to pay extra for the new OS or hassle with performing the upgrade. Neither Microsoft nor Apple has set a date for their new OS releases, but both are likely by the holiday buying season.

    This is especially true if you are thinking of buying a Windows Vista machine. Vista is slow and filled with annoying nag screens. Based on my tests of its prerelease, or beta, version, Windows 7 will be a huge improvement.

    Windows vs. Mac: Apple's hardware is beautiful and durable, and its OS is faster, easier and more stable than today's Windows. Plus, the Mac isn't susceptible to the vast majority of malicious software. Windows 7 will narrow this gap considerably, but Snow Leopard could keep Apple ahead, depending on how it turns out.

    But Apple computers cost more upfront. The cheapest Mac desktop, the bare-bones Mac Mini, costs $599. And the cheapest Mac laptop is $999. So, if price is your top priority, buy a Windows PC. If speed, ease of use and stability matter more, buy a Mac.

    Upgrading: Microsoft promises that upgrading a Vista machine to Windows 7 will be a straightforward process, preserving all of your files, programs and settings.

    It's a different story for Windows XP. Upgrading from that OS will be a cumbersome, multi-step process, requiring users to offload their files, wipe out the old operating system completely, and then reload the files and reinstall their programs. This is a particular problem for buyers of netbooks, nearly all of which come with XP.

    In addition, Microsoft's version of Windows 7 for netbooks, called the Starter Edition, is crippled. It can run only three programs at any one time, and won't allow any customization of the desktop or the use of Windows 7's snazzy graphical features. Microsoft says netbook owners also will be able to run the main Home version of Windows 7, at extra cost, but given the weak processors and graphics chips on netbooks, the experience may not be optimal.

    Apple, which doesn't make netbooks, claims Snow Leopard will be an easy upgrade on all currently available Macs.

    Memory: Neither company has released the official specs for the two new operating systems, but both are likely to require a minimum of 1 gigabyte of memory. Such specs are usually understated, so I strongly recommend 2 gigabytes, even on cheap machines.

    Graphics: In the new operating systems, adequate graphics chips will be more important than ever, because the computers will offload some tasks typically performed by the main processor onto the graphics chip. So, if possible, spring for what's called a discrete graphics processor, which has its own memory. If you can't afford this, look for an integrated graphics chip, which shares your main memory, that's as powerful as possible. One example is the Nvidia 9400.

    Processor: Microsoft and Apple say current processors will work fine with the new operating systems. The best bet is a dual-core processor. Some bargain machines use an older single-core model, which is OK for light-duty use. Netbooks, and even some laptops and desktops, come with a much wimpier processor called the Intel Atom, which struggles at some tasks.

    Touch screens: Windows 7 will include the ability to perform many multitouch gestures on the screen. But this will require a special type of touch screen, different from the ones on most tablet PCs today. A few current models, like Hewlett-Packard's TouchSmart desktop, support this, but not many. So, if you'd like to use multitouch on Windows 7, ask to make sure your PC can handle it.

    The bottom line: Don't buy more machine than you can afford, or need. But protect yourself by getting one that can be upgraded to the new operating systems.

    如果你現在想購買一臺電腦的話，有個額外的因素你必須考慮。今年晚些時候，兩大電腦操作系統──微軟(Microsoft)的Windows Vista和蘋果(Apple)的Mac OS X Leopard都將分別推出新版本Windows 7和Mac OS X。而這顯然會影響到消費者對于電腦硬件的選擇。

    因此，在這篇春季電腦購買指南的專欄文章中，我將特別關注如何選購合適的電腦以便滿足系統升級的要求。

    本指南涵蓋筆記本電腦和臺式電腦，并且針對使用電腦處理一般任務的普通用戶。它并不適用于游戲高手或者視頻、音頻或者相片處理方面的專業人士。

    成本：Windows個人電腦的價格已經大幅下降。只要不到300美元，你就可以買到一臺不帶顯示器的Windows臺式電腦。而一臺低端、全尺寸的Windows筆記本電腦只要500美元左右。如果你愿意將就所謂的上網本(netbook)──袖珍、便宜，運行逐漸過時的Windows XP操作系統，你只需花費350美元，甚至更少。即便一向不愿屈從降價趨勢的蘋果電腦也推出了低價電腦，或者更高規格但價格不變的電腦。

    購買時機：盡管電腦正在降價，但是你可能希望等等再買──如果你能等的話，直到新版操作系統上市。那是因為購買預裝新版操作系統的新電腦，通常會更容易，更便宜一些。你不必為新版操作系統支付額外的費用，或者遭遇系統升級的種種麻煩。目前，微軟和蘋果還沒有明確新版操作系統的發布日期，但是它們可能會選擇在假日購物旺季前推出。

    如果你在考慮購買一臺Windows Vista電腦，時間就顯得尤其重要。Vista運行速度較慢，而且充斥很多惱人的提示窗口。根據我對Windows 7的預先演示版，即測試版的測試，它將會有很大的改進。

    Windows還是Mac：蘋果的硬件設計優美，經久耐用，而且其操作系統比眼下的Windows運行速度更快，使用起來更加容易和穩定。另外， Mac不易受到絕大多數病毒軟件的攻擊。雖然Windows 7將縮小兩者之間的差距，但是Snow Leopard可能讓蘋果繼續保持其領先地位，這還要取決于其真正的實力。

    但是，蘋果電腦的先期成本更高。最便宜的Mac臺式電腦──配置極其簡單的Mac Mini需要599美元。最便宜的Mac筆記本電腦需要999美元。因此，如果你更注重價格，那么還是選擇Windows電腦吧。如果速度，易于使用以及穩定對于你來說更加重要，那么Mac電腦無疑是更好的選擇。

    升級：微軟承諾將Vista電腦升級到Windows 7將是一個直截了當的流程，并且會保存你所有的文檔，程序以及設置。

    對于Windows XP就有所不同了。將Windows XP升級到Windows 7需要多個步驟，需要用戶卸載其文檔，徹底清除其原來的操作系統，然后重新上載文檔，重新安裝程序，整個流程冗長而麻煩。對于上網本的消費者來說，這尤其是一個問題，因為幾乎所有的上網本配置的都是XP。

    另外，微軟用于上網本的Windows 7──初級版(Starter Edition)存在很多缺陷。它一次只能運行三個程序，而且不允許對桌面進行任何定制化，也無法使用Windows 7時髦的圖形功能。微軟表示，上網本的用戶只需支付額外的費用，也可以運行Windows 7的家庭版(Home)，但是，考慮到上網本的處理器和圖形芯片都不夠強大，用戶體驗可能也好不到哪里去。

    蘋果則表示，現有的Mac電腦都能很容易地升級到Snow Leopard。蘋果目前還沒有上網本產品。

    內存：微軟和蘋果都還沒有對外披露新版操作系統的具體規格，但是它們都有可能需要至少1G的內存。這樣的規格通常是被低估的，因此我強烈建議2G的內存，即便是在低價電腦上。

    圖形：在新版操作系統下，顯卡將顯示出前所未有的重要性，原因是電腦將會把通常由中央處理器運行的一些任務卸載到顯卡上。因此，如果可能的話，不妨使用所謂的獨立顯卡，它自帶內存。如果你覺得配置獨立顯卡的機器超出預算的話，你也可以選擇集成顯卡，它會占有主內存，功能也夠強大。一個選擇就是Nvidia 9400。

    處理器：微軟和蘋果表示，目前的處理器完全適用于新版操作系統。最好的辦法就買雙核處理器。一些低價電腦使用單核處理器，對于處理一般任務也足夠了。上網本，甚至是一些筆記本電腦和臺式電腦采用的都是略顯遜色的英特爾Atom處理器，它可能在處理某些任務時會遇到麻煩。

    觸摸屏：Windows 7將支持屏幕的多觸摸手勢。但是，這要求用戶配置一種特殊的觸摸屏，不同于今天大多數觸摸屏電腦使用的。諸如惠普的TouchSmart等幾款電腦可以支持這個功能，但是選擇不是太多。因此，如果你希望在Windows 7電腦上使用多觸摸功能，那么首先需要確保你的電腦可以支持這個功能。

    底線：不要購買超出自己購買能力或者需要之外的電腦。但要確保你所購置的電腦可以升級到新版操作系統。