Sure, Windows 7 Media Center is included with the OS, but if you can't give up your TiVo interface, here's a cheap way to roll your own, HTPC style—$60 for Nero Liquid TV software and a tuner card.
Crave posted a pretty good $70 price, a far cry from the $199 retail and $132 it runs on amazon. But a quick Froogle search turned up the same package at Fry's for $60. Considering you're getting the exact same software standalone TiVo boxes use and a USB TV tuner that can decode ATSC and QAM, that ain't a bad deal at all.
Keep in mind you will have to pay $100 bucks a year for TiVo service, the one thing about TiVo that I never liked.
Also, the tuner can only accept clear QAM, ATSC and NTSC signals, so no premium cable. Hopefully now that Windows 7 supports CableCARD so well, you'll be able to expand your channel selection soon. [Fry's, Crave]
