Upgrading, new need PSU

[pood]

Here's my upgrade specs.

evga 780i sli mobo
8800 GTS (640mb)
Q9450 proc
2x raptors
3x sata drives (maybe for if I go RAID)
2x 7200rmp ide drives
2xDDR2 dram
water cooling, I'm thinking of either getting the one of the external kits(koolance exos2) or build my own from dangerden.

I'm looking at the
corsair 620HX, because it's quiet and modular, and lots of people seem to like it.

If I plan to use the PSU for the next 3-4 years, will 620watts be enough? I'll very likely upgrade my GPU in a year or so, maybe to a 280 gtx.

the outervision PSU calculator suggest 537watts (with 15% aging) and 628w if I got a 280GTX.


Should I buy a higher one now, maybe 700watts (any suggestions for a quiet PSU in that wattage?)
OR

get the 620 HX now, and when I upgrade to a new GPU and then upgrade the PSU again (if needed?)

I may overclock it a bit too, but my priority is noise.

 

[DSF]

For a system with a GTX280, Nvidia recommends a 550W PSU with 40A on the 12V rail as a minimum, for what it's worth. Considering that you're also running a quad core processor and seven hard drives, I'd probably step up to the 700W range.

 

[Zap]

My rule of thumb is that a hard drive can pull up to 15W of power (mostly +12v, some 5v). GTX 280 can theoretically pull 375W (PCIe 2.0 = 150W, 6 pin PCIe 75W, 8 pin PCIe 150W) but most likely pulls between 225W and 300W (PCIe backwords compatibility, will not use max of the 8 pin). What's the TDP of that proc?