I used it. I had two 7900GT KO superclocked I paid 289.99 for at Newegg. I used the step-up program about 87 days after I bought them. They gave me the 289.99 credit, but the 8800GTSs I wanted were on backorder, so I had to wait. About a month later, they said my step up was ready and that i had 14 days to pay for the new cards. I waited 12 days and paid for both cards, then i followed their instructions for mailing them MY cards, which, over the holidays took FOREVER. My comp was down, so i bought a couple of cheapie 7300GTs (which suck even in SLI) to run. I had those for about 2 weeks, then my cards came in, and i installed my 8800GTSs. Then I took the 7300's back to Best Buy for a refund
I wound up paying the difference between two 289.99 cards and two 499.99 cards, so i shelled out 410 for them, but the kicker is that I got 289.99 credit for 4 month old cards that would have gone on eBay for quite a bit less. Newegg had the 8800GTS for 469.99 anyway, so there wasn't much difference. I would say, if you bought a high end card and wanted to trade it for another high end card where one card is over priced (as high end cards are) then do it. Trade your 7600 for something awesome, not something played out. Get a DX10 part.