Which 8800GTS is it? G80 GPU or G92 GPU? If its the G80 one, then those temps are quite normal. If its the G92 version, those temps a a bit warm, but nothing I'd worry about.
A PSU with lower wattage doesn't generally affect GPU temperatures.
thanks for that - mine is a g80. i'll monitor for now but keep an eye out for a bargain psu...