also im not too sure about this i assume i can but i just wanted to make sure that say if i wer to get 1 geforce 7950 GT 512mb with the pc and then when i save up later get another 1 2 put them in sli formation would that be possible?
or would i risk taking apart the carefully made ready made pc?

You would need to make sure you have an SLI motherboard and an SLI PSU.

Looks like a pretty good setup. Nothin too fancy, but it's nice. More RAM though, that's always good.

It's not a bad computer at all....

I wouldn't get such a high performance DirectX9 video card - as DirectX 10 Cards are here now...get one of those instead if you can.

I would also stay away from SLI - it's not worth it.

Also go for at least 2gb memory.

After having a closer look at the specs...there are a few things that could be better for a gaming machine

1) Power supply - only 400watts - this is pathetically low for a gaming machine in this day and age - you want at LEAST 550watt
2) Sound card...it's 7.1 - any real gamer will tell you - Headphones are the only way to play games...get a Creative Audigy4, use headphones with EAX - you'll be able to hear exactly where footsteps are.
3) Not enough memory. You want at least 2gb to be able to play the latest and greatest games
4) Make sure that keyboard & mouse is not wireless - wireless is shocking for games - especially when the batteries are close to dead
5) Wireless network adapter - again...useless for games.

is this psu ok? ThermalTake TR2 500W Black Silent +ATX 12V 2.0 PSU, 20pin +4pin SATA ready available at Micro Direct Ltd UK

and is this motherboard ok?
Kikatek.com | (90-MIB040-G0EAY) Asus A7N8X-XE Motherboard - Athlon 64 X2 Socket AM2 NVIDIA nForce 590 SLI MCP ATX Dual Gigabit LAN