I'm still hunting around for a suitable new PC and I'm gradually toning down my requirements as I just don't think I'll make proper use of the very very latest technology (ie, 8800GTX and Quad core processor) and the price tag is putting me off at this time of year...
I've found a base unit which has an E6600 cpu and an 8800GTS card but which is powered by a 550W PSU. Is this enough? The only upgrade option is a 900W PSU, but it's another £100 and seems like overkill.
Providing that the psu is of good quality, it should work. Problem is that it doesn't allow much room for adding any hardware or overclocking. The 900wt psu is overkill, unless you're doing SLI with a lot of hardware, watercooling, etc. Too bad there isn't a 750wt optional.
If looking at the present system, I think I'd go ahead with the standard psu for now and just figure on upgrading it when and if more hardware is added or overclocking done.