Re: planning on new pc sometime this year..
Do you have the raptors on hand?
Otherwise I recommend just getting a Caviar Black 64mb cache or Samsung Spinpoint F3 or SSD's.
Raptors aren't really worth it anymore, as normal SATA III hard drives are approaching their speeds at a much lower cost and with much more room.
As far as the motherboard goes, the EVGA 3X SLI is a great board, though you may want to look into a board with SATA 6Gb/s support.
Also I assume you mean 1Tb and not 1Gb drives?
Also, your 750w PC Power and Cooling PSU "MIGHT" work, but I wouldn't risk it with TWO GTX 470's.
You'll be drawing on full load an easy 500-600w.
Not including overclocking.
So if you start overclocking you might reach that PSU's limit.
Though it doesn't cost you any additional money to give your current PSU a try.
I would at first try your PSU, and try overclocking with it, if it can supply enough power... Great!
If it can't, THEN I would buy a new one.
No sense in wasting money on a new one already if the PC Power and Cooling can actually power that system.
So give it a try, and if it doesn't work, you can then go buy a new one.
And if you want to use your rig until you can get a new PSU, just take one GTX 470 out and I'm certain your PSU can handle a single one.