I got the XTi in May as my first dSLR and have greatly enjoyed it ever since. I had a similar budget to yours when I was looking around. I went to several expositions and tried the a100, d40, d80, XTi, and 30D. What really sold me was having the battery grip on the XTi since it makes it bigger and better balanced with long lenses, plus a shutter for vertical photos. I could not stand the illogical button layout on the a100 (IMHO). I have shot everything from an air show to several weddings and have gotten excellent pics with it all. The hardest part was finding sharp lenses (especially on the Tamron). I would recommend getting the 70-300 since its possibly the best non-L Canon telephoto out there....the 17-55 IS is nice but very expensive (and arguably not worth it).
What I bought for $2,200:
$680 Canon XTi
$550 EF 70-300 f/4.5-5.6 IS USM
$450 Tamron 17-50 f/2.8
$100 filters
$140 Canon battery Grip
$200 2 Extra batteries, CF Card, cleaning supplies, bag
$80 Canon EF 50 f/1.8
What I bought for $2,200:
$680 Canon XTi
$550 EF 70-300 f/4.5-5.6 IS USM
$450 Tamron 17-50 f/2.8
$100 filters
$140 Canon battery Grip
$200 2 Extra batteries, CF Card, cleaning supplies, bag
$80 Canon EF 50 f/1.8