Hi Froggy
First of all, welcome to PC Pals
I hope you join in with the fun and enjoy yourself here ... we're a friendly bunch
Right, your problem
Have you downloaded all the latest updates from Microsoft ? If you have, you will certainly have installed one that makes your machine run slower ... there is some info about it
HERE This may be part of the problem
The next thing is to check whether your HDs are set to UDM mode, this is done in the Control Panel, System, Hardware tab, click on the Device Manager button, and then expand the IDE ATA/ATAPI controlers route. Double click on the Primary, and then click on the Advanced Settings tab. The drive should be set to UDMA Mode.
Are you sure the BIOS has detected the correct Front Side Bus speed for the CPU ? Is this CPU running at the correct speed ? You will need to enter the BIOS to change that if it isn't. (you will see the CPU speed when you first click on System in the Control Panel as above)
I'm sure more people will be along with more things to check, unfortunately I have to go now. Hope you get it resolved quickly.