While setting up an old computer for my grandparents, I decided to add an inexpensive video card as the integrated Radeon Xpress 200 doesn't handle their 1920x1200 monitor very well. I picked up a Radeon HD 4550 card (Gigabyte's GV-R455D3-512I), but when I installed it, the system became slow as molasses. Additionally, when I try to "rate" the system in Windows 7, I eventually get an error message that the computer cannot complete the Direct3D 9 Aero part of the assessment.
Normally, I'd just RMA the card and try with a new one, but my grandparents live several hundred miles away, and I doubt a replacement card would arrive before I have to leave. My question for all of you is whether this sounds like a problem with the card, the system or the software. Installing the most recent ATI drivers didn't help, and I was unable to find an option in the BIOS to disable the onboard graphics. Instead, there was an option to choose which graphics to initialize first: PCI, Integrated or PCIe.
The system is an eMachines T6520. CPU-Z reports that it's got a Micro-Star MS-7145 motherboard with an AMD Athlon 64 3400+ processor. It's been upgraded to 2GB of RAM and Windows 7 Professional (32-bit).
Thanks in advance for your help, and please let me know what additional information, if any, would be useful.