The one I had was the dual-core Pentium SU4100, so take this FWIW.
It will play WoW on low settings at 20-25 FPS in lower-population areas. Games like CSS and Portal will be very low FPS, usually in the 0-10 mark. UT2004 runs OK, and other games in the 6+ year old mark run fairly good. Serious Sam HD TFE runs in all low settings @ 800x600 very well actually.
EDIT: I should mention that CSS might run decent in DirectX 8 mode at all lowest settings and 800x600, but that all depends on the map. Complex maps will choke the 4500MHD.
I wouldn't buy anything these days that isn't dual-core or at least hyperthreaded. That's just my opinion.