XTi's are good.
But I'll play devil's advocate for you so you can make your decision:
1. One thing I don't like is that they come with a silver and black body =P I personally like black bodies so they don't reflect off any surface at all, but even in black it's not 100% non reflective. But silver? I think it defeats the purpose and shows it's less than professional, even though you can get awesome pictures out of it.
2. The shutter sound is like an electrical squeek, while the 30D, 40D, 5d, are like, CATCHUCK! The electric squeek sounds kind of... well... lame. That's just the sound though, lol! I love my D80's crack when the shutter hits. It's so satisfying, sounds like you just REALLY took that picture. The Nikon D2H also sounds badass when shooting at 8fps? So get into the 30D + models of canon to get that real nice many click.
3. From what I hear, the layout of buttons etc. is quite different than the 30D and up. So comparing and getting help from 30D + people may be a little more difficult, whilst someone with a Nikon D2X can help someone with functions of a D200, D80, etc. (what are they at now? D300 D3 etc?)
But really, otherwise, they're awesome =)