if you take the 734ghz / 10 gives you the base clock. 737/10 gives you the new one. so you will gain .4 frames per second. so it might be noticeable, but only barely.
You would be better off upgrading to a newer card, like a gtx 460
You're telling him to upgrade to a card that's two generations old and you don't even know what he has now. Also, gpu base clock rate and fps aren't linearly tied, so you can't tell him 3Mhz overclock will give him .4 fps.
To OP, if you're getting BSOD, it's probably either a gpu driver issue or memory issue. If you can't make out what crashed on the BSOD, you should uninstall and reinstall your GPU drivers as a first step.