intel is really trying to prove thet they are better at gaming, but they really arent, although you can get away wit some less taxing games at 720p/480p, i suggest getting at least a 6670 if you want to do any gaming
if you want to play games with integrated gfx, get an amd a8 3850 or new 3870k apu. those have far superior igp than intel's hd 2000/3000.
if you want to play games with intel processor, get a discreet gfx card. cheap cards start from radeon hd 6670 to higher end nvidia gtx 560 ti to even higher radeon hd 6950 or nvidia gtx 570.
here's from intel's website - list of 'playable' games on hd 2000/3000:
This information is provided solely as a convenience for customers. The list is not intended to be complete or all-inclusive, and is subject to change or revision without notice.
Individual game experience may vary depending on the game application version and computer configuration.
The Intel HD 3000 is basically equivalent to a Radeon HD 5450. You can Google for HD 5450 benchmarks to see how well it does.
Not all Sandy Bridge Core i3/i5/i7 have the Intel HD 3000 graphics core. Only the i3 CPUs ending with the number "5" will have the HD 3000 graphics core as well as all "K" models of the Core i5 and i7. Everything else has the slower HD 2000 graphics core.