Look at these benchmarks and then 'LoL':
http://www.theinquirer.net/gb/inquirer/news/2007/11/27/low-gpus-leave-lot-desired
HiS HD2600XT:
Crysis - DX10 - 1024x768 0xAA 0xAF : 7.5FPS
Call of Juarez - DX10 - 1024x768 0xAA 0xAF : 18.8FPS
World in Conflict - DX10 - 1024x768 0xAA 0xAF: 15FPS
Company of Heroes - DX10 - 1024x768 0xAA 0xAF: 20FPS
But of course, why would you play at 1024x768 on a 22 inch screen? turn resolution a bit higher and then you get the 10FPS i was talking about, nevermind the AA and AF
And consider the system that was used on the tests has:
Intel Core 2 Extreme QX6800 @2.93 GHz
Zalman CNPS7700-Cu Cooler
Gigabyte P35-DQ6 Motherboard
2GB Corsair Dominator PC2-9136C5D (1142 MHzstock 5-5-5-15)
250GB Seagate Barracuda 7200.10 16MB cache
The results are much more positive under DX9, hence my suggestion towards XP rather than Vista.