450W = overkill :
i´m running a AMD64-3200+ system with an ATI 9800pro, 2 optical drives, harddisk, waterpump etc with an old 350W enermax and there is still power to spare
even 400W-PSUs are way over the top... and the new GF-6800 cards may have two power connectors, but the power intake is not that high
they only need the double feed to have a stable voltage
i´d reckon even a 300W-PSU would suffice for up-to-date systems as long as it´s good quality!