I'm a long-time Media Center user - dating back to Media Center 2005 (which I started running in early '06.) Having been thru a few versions now..... MC for Win7 rocks. It is the most stable, most flexible, and most tweakable version of MC to date. I absolutely love it.
It is, though (and, this is By Design) still a Nervous Nelly about your choice in TV tuners - you absolutely should use tuners that are rated for Media Center (it has specific hardware and driver requirements, particularly for analog tuners.)
And, experience has taught me (and, a lot of other MC users, too) this:
Media Center works best by itself. If you want a truly stable Media Center, use it as a dedicated Media Center box. Install on it only what it needs to complete its mission.
(You'd be amazed at how short the Programs list is on my HTPC (which has run Win7 since Win7 launched, and is still running that same Windows install (plus updates.))