careful with modding the app to make an unsupported gpu work.
some have had success, others very odd technical problems.
Your safe bets are:
Quadro4000 – yes a bit expensive, but works and works well. CS 6 workhorse.
GeForce GTX 285 – cheaper if you can find one. works well, almost as fast as quadro4000
I was planning on the GTX 285, then decided the Quadro was worth the extra money.
After using it for 6 months in 2 different edit suites, I’m glad I got that one.