Mining bitcoins? This graphic card is a good choice for a good price. Is capable of 450MH/s and probably more if is overclocked. Down bellow I will list other other graphic cards what are not necessarlly cheaper, but are better that 7950. Note: I didn't test the graphic card myself, but according to Mining hardware comparison this are the values what you should expect from it.
|600 - 700 MH/s - Radeon HD 7970 OC with Boost||$451.95|
|400 - 450 MH/s - Gigabyte Radeon HD 7950 OC||298,27 €|
|600 - 700 MH/s Sapphire ATI HD 7970 Grafikkarte||352,00 €|
|700 - 750 MH/s - Radeon HD 5970||$799.99|