ATI Radeon HD 3650 PCIe issue

I've performed a clean install of windows 7 and it loaded the driver for my video card. (Radeon HD 3650 PCIe 512MB) Windows 7 is sooo slow. I looked in the process explorer and the System Interrupts is taking 80-100% of my CPU Usage, its crazy. I can barely do anything.
I think/have a feeling, that its the card because I took it out and used my on-board video and everything ran perfectly fine and speedy and snappy.
I dont really know what to do to fix it. I've tried using different catalysts but, still, same issue. Shouldn't it have worked with the defaul built-in windows 7 drivers? Im confused, and frustrated. Any help would be awesome.

my machine
Processor : AMD Athlon 64 3200+ (2.2Ghz)
Memory : 1.5 Gig
eMachines Model T6209

Does your system BIOS have the option to shut off the on board video?

This was suggested in the installation documents of my HD4550, but my BIOS seems to deal with it, and I have no option to disable. In my case, it was no issue, but if you can shut yours off explicitly it should be tried (if you haven't already).

My BIOS doesnt have an option to officially disable it. I can set the bios to look first for video either on PCIe, Onboard, or PCI slots. It's always been set to PCIe.

Mhmm, Its 32-Bit. I know its the 3600 series, same thing it reveals on my XP device managers. It's never been identified as the HD 3650 as on the box, always the series label. I've looked all around for solutions but I always get pointed to the AGP version of the card, not the PCIe one

How interesting. I went browsing on the AMD site and their little sub-section of forums and found someone having the same issue with a Radeon HD 4xxx card.
They had the same issue, where the card would make things slow, and if they took it out, it worked just fine.
They solved it by going into device manager -> System Devices -> and disabling High Definition Audio Controller. Why it's that, I have no real clue.
I didn't have the same card, but, figured it was worth a shot. So I went and did it.
Immediately after, I was so relieved. It fixed the issue. My CPU usage went down to 10% and doesn't go any higher now when its idle. Windows 7 is now running smoothy, speedy, and snappy, the way it should wewt! haha, i'm excited