When you got your first experience with Bitcoin money you may want to try bitcoin mining on your PC. First of all you need to get configuration information of your PC and check if your hardware capable to run bitcoin mining fast enough. As you know, CPU mining currently is faster than GPU mining more than 100 times. So it's very important to have really fast video card on-board. NVidia GeForce GPU cards are surprisingly slow in comparison to AMD ATI Radeon HD. It's pointless to run bitcoin mining on NVidia cards. Here list of most effective cards to run mining:
Best performance/cost ratio have ATI/AMD Radeon HD 5xxx series cards:
Radeon HD 5750 ~140 MHash/s - 90W
Radeon HD 5770 ~190 MHash/s - 110W
Radeon HD 5830 ~260 MHash/s - 175W
Radeon HD 5850 ~290 MHash/s - 151W
Radeon HD 5870 ~380 MHash/s - 188W
Radeon HD 5970 ~640 MHash/s - 294W
AMD Radeon HD6xxx series cards are more expensive and got lower performance/cost ratio:
Radeon HD 6670 ~110 MHash/s - 50W
Radeon HD 6790 ~190 MHash/s - 150W
Radeon HD 6850 ~210 MHash/s - 127W
Radeon HD 6870 ~280 MHash/s - 151W
Radeon HD 6950 ~310 MHash/s - 200W
Radeon HD 6970 ~370 MHash/s - 250W
Radeon HD 6990 ~690 Mhash/s - 375W
Full hardware comparison list for Bitcoin mining with all GPU and CPU performance data you can find on wiki page. When you determine your mining speed in MHash per second value go to Bitcoin GPU hardware mining calculator and calculate how much money you will earn running your mining rig for week or month.