Not exactly the same conditions, but I managed to get my ATI Radeon HD 4650 AGP working with a Gigabyte mobo under Microsoft Windows 7 Pro 32-bit.
I had to set the AGP aperture to 8 in BIOS (computer set up). The driver I used was for the Gigabyte GV-R465D2-1GI which is a variant of the HD 4650.
Please try the Windows 7 driver from the Ggabyte site: GIGABYTE - Graphics Card - ATI - PCI Express Solution - Radeon HD 4000 series - GV-R465D2-1GI
Also try the AMD Windows 7 driver for AGP HD4650. Make sure to select the AGP package, not the PCIe version: Global Provider of Innovative Graphics, Processors and Media Solutions | AMD
I initially installed the AMD 11.5 AGP hotfix package (driver version 8.85). System would blue screen from the ati2mtag.sys driver. I decided to try the Gigabyte driver since I was using a Gigabyte motherboard. The Gigabyte driver worked, but occasionally the video would freak out with this scrambled pixelation pattern causing Win 7 to throw an exception then blue screen. I then experimented with AGP aperture finding that 4 was too low (driver wouldn't load) but 8 was best. The 256 setting was too high, causing crashes often. Thus I went the other way, reducing the aperture until a stable point was found. Please try it.
The Gigabyte driver is actually AMD driver version 8.66.
Here are my system specs:
- Gigabyte GA-8IPE1000-G rev4 motherboard.
- Intel Pentium 4 cpu 3.4 GHz.
- Windows 7 Pro, all updates applied.
- 4GB RAM installed.
- ATI Radeon HD 4650 1GB RAM 2xDVI 1xS-Video.
- 500GB Western Digital SATA Caviar Green HDD.
- LG BH10LS30 Blu Ray RW SATA supermultiblue.