I still run win98 and I'm quite happy with it..and I'll run it until billy boy takes my win98se cd from my dead cold hands.. (paraphrasing Charlton Heston's speach at the NRA)

however, nihil is quite right.. the defrag that come with windows sucks.. you either have to run it in safe mode or make sure that all processes are shut down.. even then it still sucks.
I'm a big fan of voptxp (formerly called voptme) but there's a few other defrag utils that are equally (or almost) as good as voptxp..

(sorry aeallison.. just my 2 cents.. but not a bad tut overall..)