Microsoft's set a date, laid out their prices and started taking orders, but cheapskates: don't fret! You've still got until the 20th to get a near-finished version of the OS for free. Which you should, for all kinds of reasons.
The obvious ones: Microsoft is still using this to test for bugs, so you using a late-stage Release Candidate now equals faster security and usability updates after Windows 7 later. But more importantly, you get to try Windows 7 for an extended period now—you'll have until March before Microsoft starts forcefully shutting your computer down every two hours—before you commit to buying. Thursday may be your last day to nab an official download, but even then, Microsoft says they'll be handing out license keys for a while; you'll just have to supply your own copy of Windows. Microsoft is practically asking telling you to torrent Windows.
You should try it now, but wait to buy—prices will almost certainly come down before or after launch—maybe not very soon, but certainly before your RC expires and/or becomes an aggressive annoyance.
A few things to chew on while Windows 7's works through its prerelease "awkward phase:"
• A characteristically confusing upgrade chart, which won't help you at all.
• A much less confusing guide to Windows 7's price tiers, as well as a glimpse at some expired deals that you can expect to see again in a few months.
• A full review of the final, soon-to-be-released version of Windows 7, in case you're still not convinced that a free copy of the best version of Windows, ever, is worth downloading.
• Everything else you need to know to enjoy your borrowed copy of the OS for the next six months or so.