you will get a pretty good performance boost if you use a velociraptor and properly configure ACH10 drivers,however many people just throw in the velociraptor as an IDE device, that surely wont give any boost
maybe youll want to give a try to system restore, essentially is a back-up/ restore of the registry
start/all programs/accesorioes/system tools/system restore
It has saved my bacon several times. good luck