Mobility Radeon HD 4550 is an entry-class level GPU part of the Mobility Radeon HD 4000 Series released by AMD in 2009/2010.
There are many versions available from GDDR3 (and DDR3) type to DDR2 and from a 64 bit bus to a 32 bit bus. This is the GDDR3 version with a 64 bits memory bus.
It only supports DirectX up to 10.1 so DirectX 11 games aren't supported. The performance should be enough to play demanding games like, Crysis 2, on the lowest settings but with unattractive resolutions while very demanding games, like Metro 2033, are probably unplayable to the lowest settings. Less demanding games should be playable on medium settings, depending on the resolution + DirectX version used.