Required Power Supply for new system?

I am in the middle of building a new system (looking to build a monster/killer system). I've pretty much decided what components I want to get, the only problem is I have no clue which Power Supply is needed/recommend. I am not looking to be cheap (money isn't a huge issue) but still wish to stay resonable.

My new system profile is the following:
[Profile]
CPU: INTEL Core 2 Quad Q9450
MOTHERBOARD: Asus X48 DDR3 (still debating on which one)
VIDEO: ASUS/SAPHIRE 4870 (Arctic AccelS1 rev2 with dual fans)
RAM: 2x2G OCZ DDR3 PC-12800 1600 MHZ (Platinum or Reaper HPC)
HDD: 4x Western Digital SATA2 500GB
2x Western Digital PATA 320GB
Case: Full ATX Tower with 5x 120mm & 1x 200mm fans

Question is...
a) how powerfull of a Power Supply do I need? 650W? 700W? etc...
b) what are the prefered manufactuers & models?

Any advice would be greatly appreciated.
Thanks,

Nice system. If you are getting something that nice get a decent PSU.You may want to xfire in the future so go big 850w+ Check out these sites to do a check of what you need.
http://web.aanet.com.au/SnooP/psucalc.php
http://www.corsair.com/psufinder/default.aspx
http://extreme.outervision.com/psucalculator.jsp
As for a brand I think Corsair are awesome, but there are others.

Corsair, Etasis, Zippy, PC Power and Cooling, Silverstone, Seasonic, Some Thermaltake, Antec, Enermax units those are some of the better or best retailers out there that I can think of off the top of my head.