I just thought I'd mention that most Vista users should notice a large decrease in load time using
ReadyBoost. Basically, all you do is pop in a flash drive and chose the ready boost option. Windows will set it up with good defaults. This basically caches the files used during loading for faster access.
[EDIT] I think everyone should also be aware that prior to service pack 1 (SP1), Vista had a serious flaw that made file access increadibly slow, even with readyboost. All Vista users should update with the latest service pack if they want to fix this issue. This is stated as an IT professional, but you do it at your own risk.