I agree Colin Mcrae 2 is pretty damn good. The sound effects when you go off course and whack into the trees is enough to make you cringe. It's made by codemasters and you can download a demo from their site. As far as where to buy it good luck. You won't find it at Best Buy, Circuit City or Comp USA. Try your mall game stores etc.
Colin McRae Rally 2 is the best all-rounder, really....... really schweet whether you play a championship or want a quick blast. However, if you are really after realism, you can't go wrong with Rally Championship (a steal at £5.99 ) which is just too good, but only really for you if you have a lot of spare time, as the stages are all "proper" length, ie they take aaaaaaaaagggggeees to complete , rather than the 3-4 minute blasts which are CMR2. Rally Trophy is meant to be excellent, too. Like Championship but retro..... schweeeeeet I think CMR3 is meant to be out relatively soon, too. EDIT// just noticed you only said racing games but rally in particular..... if you are partial to a bit of Formula One, look out for Geoff Crammond's Grand Prix 4 this summer (~14th June), tis the game for the racing game connoisseur