As said not really, the big issue being how much electricity it will use verses what you can profit from it, do you leave your PC on all the time?  If so then having a 7950 running 24x7 will only add an extra 180-ish watts or so load but if your PC stays off a lot then you will have an additional 300w + watts obviously depending on your PC spec which will soon add up over a month and so make your profits very minimal after you have covered the electric to the point of whether it would be worth doing at all, especially at the moment as difficulty has gone up and its taking longer to produce BitCoins.

A while ago I was running a single 7950 @ 500Mhash and after a week of 24x7 running I barely made 0.1 Bitcoin, you think times that by 10 = 2.5 months almost to make a single bit coin! 

Might be worth looking at LiteCoins like its been mentioned