AMD M880G ATI Mobility Radeon HD 4250 2 GB RAM
Therein lies your problem. That's an extremely low-end version of the 4xxx series. You'll need to lower the visuals to match your card.
*EDIT*
Also, here are the actual requirements from the Steam page:
Minimum:
Graphics: HD Intel Graphics 4000 or NVIDIAï½® GeForceï½® 8800 GT (512 MB) or ATI Radeon HD
4850 or equivalent
Recommended:
Graphics: NVIDIAï½® GeForceï½® GTX 550 ti 1GB ram or or ATI Radeon HD 6XXX or higher
Note that a 4850 (not a 4250) is the minimum requirement.