I *just* bought a refurb i5 mini-desktop (HP COMPAQ 8200 ELITE) to use for gaming. Civilization V, which runs okay on a i5 laptop but overheats. It got here yesterday and I haven't even plugged it in yet. I'll probably be installing Win 7 updates and antivirus on it tonight.
I have a Sapphire HD5450 low-profile graphics card that'll fit. (I bought it on sale really cheap last year for another project that never materialized.) Not sure if it will be any better than the Intel integrated graphics or not. Hopefully it'll let me crank up the video quality settings.