Ok, thx Kokjo!

As for nvmind, maybe I could help a bit (despite my NoobNess)

The rest of the system with the 5770 in it is nuthin special at all (2GB DDR2, P4 3.0 Ghz, XP 32bit)

I am using GuiMiner with the flags: -v -w128

I have the cards Memory clocked down to 600 (MSIAfterburner wont let me go lower) and the Core clocked at 925.

Fan locked in at 85% and the card is running very stable at between 80c-85c