Smoothing out how to enable it? (FlatOut: Ultimate Carnage)

I understand that antialiasing can include only the happy owners of GeForce 8800 cards and above, himself owning a 7900GS would be very glad to include at least double smoothing! Can anyone found the solution and have some ideas?

PS. In the settings of the graphics card drivers enable antialiasing doesn't help those people who can only say buy a new graphics card, etc. are asked to refrain from advice!