I got my XBox a couple of months ago and it has a Thompson DVD drive. About a week after I got it, certain discs (mainly SSX3) would start giving dirty disc errors. Rebooting over and over eventually fixes the problem.
After reading around, it seems this is a common problem w/Thompson drives. I just ordered my modchip, but I'm wondering if I shouldn't take it back to BestBuy first to get it replaced w/a unit w/out a Thompson drive before doing the mod.