Need advice on computer I'm buying

[Hotnutz]

I am getting this setup dirt cheap for $300
It's a Gateway DX4200
this link is the DX4200-09 which is a different processor but you get the idea http://www.gateway.com/systems/product/529668220.php

Quad core processor AMD Phenom X4 9550 / 2.2 GHz
4 GB DDR2 SDRAM
ATI Radeon HD 3450
640.0 GB SATA Hard Drive

Although this is nothing amazing I am considering adding some more goodies to it.

2x 32 GB Solid State Disks in a raid setup
a new Video Card yet to be decided to run 2 moniters
4 GB more ram (for a total of 8gb)
and a second moniter for more screen real estate

What is your opinion on this...
What Video Card would you suggest as a budget option....
What do you think about the SSDs and would 32gb be enough for 5 copies of wow?
Would this setup even run 5 copies of wow??

Any advice/suggestions are much appreciated.