I have just upgraded my main hard drive from an old ata-66 12gb to a new DiamondMax plus9 80gb and while it seems to have better transfer and access times my systems 3d graphics performance has nearly halved. I used 3dmark 2001se to benchmark my old system and acheieved a score of about 11500 on the default settings but after installing the new drive i could only score about 7000! I have checked that dma transfers are enabled and I'm using an ultra dma cable with no other drives on the same cable, I have the latest Nvidia drivers and DirectX 9. My system supports udma-133 drives so I can't work out the problem!
Oh I suppose i'd better give you my system spec,
MSI KT3 Ultra2 board
256mb DDR Ram
Nvidia Geforce 4 Ti4400
Maxtor DiamondMax Plus9 80gb