Agreed i use a 350D with a 28-135 IS USM, body was £250 and the lense £212 + £4 for a hood, and that is so far doing me fine for Surfing, kitesurfing, kitebuggying, landboarding, ATB. Which are fiarly quick sports and im getting some good shots, whole lot better then my OLD P&S. So i recon for £4-500 you can get a good camera im no expert[newby ] but thats what im using and its fine for what i want. Id Recomend the 450D XSI seems to be good had a play in currys love the screen its HUGE and comes with an 18-55 IS lense which seems pretty good to start with.
Rebel XSi=$700 70-300=$550 30D=$400-500 85 f/1.8=$250(used)-340(new) Soooo...how was my recommendation expensive?
i'm with vers. 30D would be the best bet for sports. the 85 1.8 lens would come across a little inflexible for a beginner, however, although it would make for a great way to quickly learn. (also i must admit, 4boys4me was a rather unfortunate name to choose)
To be a bit more clear, a good kit to go with is the 30D, 18-55 IS, and the 85 f/1.8. When you come across a bit more money to spend then invest in some longer zooms like a 55-250 IS and or 70-300 IS.