After installing an HIS 4350 ATI Radeon card into my vista machine, instead of improving anything it has slowed my computer to the point of being basically unusable. Its as if the CPU is filly loaded but yet it isn't !

I have un-intsalled all older cards and drivers and installeed the latest driver for my card from the HIS site (serveral times) with no difference.

Any ideas on where I can start looking

Computers & Internet - HIS - HD 4350 Silence DDR2 PCIe, PCI Express Video Card