sounds about right if going from the initial release to current. if i recall correctly microsoft said they were not going to release a service pack for win7, force everyone to update like you. My only suggestion is to avoid the language packs, they are truely optional, and in the past have caused probablems.
Oh and when you are looking at the system monitoring, make sure that the system processes are being shown too. Could be that there is a lot of drive indexing and stuff going on. Sometimes it isn't very obvious though what is causing all the drive activity (had to look at a Vista machine recently which was terrible for it, switched off all the indexing, prefetching etc and was still pretty bad, so could have been the antivirus on that occasion).