I have two XFX 5870s that just need new fans. I used them before I heard about bitcoin, so they were only used for gaming and a maybe a couple of months sporadically on BOINC projects. I thought about fixing them and building a 2cd machine just to mine, but I would have to buy all the other parts too. Everything was working great on them (ok maybe not always ATI's drivers lol) until the fans died. One fan completely froze up and one just sounds horrible.
If you might be interested shoot me a PM.