Have you already replaced the PSU (I saw you bought one, just want to make sure you got it already)? I wouldn't run any tests until you do (as your old one is definitely shot). And trying an old card is a great idea (that is what I did when my 4850 was bad to prove it was the card).
Yeh, i bought it put it in, loaded up my infamous Ubuntu, works fine, i just want my card! (I dual boot with Windows Vista) I cant find my old card atm lol, its some where ill post back when i put it in.