I've never set up a Windows Media Center before, so I putter out here. But as you're configuring WMC, it asks you what input devices you want to use, and your input device appears to be a tuner card of some sort. You need to tell WMC to use that tuner card, and to treat it like an analog (NTSC) TV tuner. Then WMC needs to do a channel scan with that card, and the only channel it picks up should be channel 60, assuming your 622 is turned on and pushing video via coax.
Frankly, I'm not sure that you can use TV2 on a 622 to view recordings and change channels. If you could do it with XP's Media Center, there should be no reason that Vista can't, but you're asking a lot out of a piece of free software. I'm pretty sure I've seen WMC control a 622/722 on TV1 when connected via S-Video, using an IR blaster to change channels and whatnot, but at that point, you'd be better off using a less-powerful [complicated] receiver.
Tip: if you can figure out how to set the agile modulator on the 622 to a lower channel, such as channel 21, you should do that instead of 60. Typically, the lower the channel number on the agile modulator, the better the picture quality of it's output.
