Try it a Geforce FX 5500. 99.99% there will be a slow down (man I need a new computer)
i think it will run fine, if you just turn down some graphics..
heres one of there preformace results:
CPU: AMD Athlon(tm) XP 2500+ (Barton), 1833 MHz
MBO: ABIT AN7, nForce 2 400 Ultra
1024 MB DDR (2x512 DC 333 MHz)
Saphire Radeon 9800 Pro 128 MB
Seagate 80 GB SATA I (OS and game)
Seagate 250 GB SATA I (paging file)
5.1 sound card on board (N/A)
OS: WINDOWS Vista RC 1 Build 5600
Graphic Drivers: ATI Catalyst for WINDOWS Vista RC 1
MBO: Not available
IMPORTANT NOTES: 1. Since no drivers for MBO were installed there was no sound in benchmark. Therefore, results are slightly (1-3%) better.
2. Also note that paging file was located on the second HDD which increased performance by 15 to 20 %.
These options were selected:
Resolution: 1024x768
Antialiasing: None
All options High
V sync: OFF
1. SM 1.4, Lighting: Normal
Score: 11603.4
Max FPS: 120.0
Average FPS: 60.3
Min FPS: 5.0
2. SM 2.0, Lighting: Soft
Score: 10309.0
Max FPS: 100.0
Average FPS: 53.4
Min FPS: 10.0
3. SM 3.0, Lighting: HDR
Not supported
I'm under the impression that 64bit HDR requires a 64bit CPU hence my comment. I'm not an expert however.
i guess your right

atlast a game that will take advantage of 64bit.
Oh and Unreal 3 will support 64bit too