By now you've undoubtedly heard the news: Until July 11 (or while supplies last), you can preorder the Windows 7 Home Premium Upgrade for $49.99.
After the deal expires, that same upgrade will cost you $119.99. Needless to say, if you're interested in Windows 7, now's the time to buy.
My advice: buy two. Then, after Windows 7 ships (on October 22), turn around and sell your spare copy for $100. Obviously that's $20 less than the list price, meaning you should have no trouble moving it on eBay, Craigslist, or wherever.
At the same time, you recoup 100 percent of your investment and get Windows 7 to boot (literally).
Risky? A gamble? Perhaps, but to this day upgrade copies of Vista are selling on eBay for $100 and more. And that's two years later. The only real downside is that you're out $100 for about four months. Worth it? Let me know in the comments.
In the meantime, keep in mind that if you're a Windows XP user, there's no automated way to upgrade your system to Windows 7--not without wiping your hard drive. (Vista users, however, can upgrade directly.)
That means you'll need to back up your drivers, data, and the like, install Windows 7, restore your stuff, reinstall your applications, etc. It's a hassle, but in the end you'll have an outta-the-box-fast PC with a spiffy new OS.
And a free one at that.