group policy problems

Ok, here’s the deal… I just purchased some new Dell (Win XP Pro) computers for my office network (Win 2K3 servers). I’m using group policy to manage the settings on the workstations – the same policies have been in place for about 4 years now. The problem is, the policies don’t seem to be applying properly on the new computers. I’m putting them in the same OUs with existing computers, but using the same username, I get different results logging onto a new pc as opposed to logging onto one of the existing pcs. I’m thinking there’s probably some issue with the local security policy on the new computers, but I haven’t found the problem yet. Anybody have any suggestions?