Aiming to upgrade, possibly a whole new rig - Budget of £650 maximum

[SupaBastad]

[img]http://puu.sh/c9lUN/6159f6419f.png[/img]
Current setup. It's a pre-built acer piece of crap.

I'm thinking of just getting a new motherboard, GPU and case (mobo has no PCI slots and case is tiny) but if it would be too much of a bottleneck I'll go for a new setup if anyone can provide one.

My main question is if I get a GPU such as the 750ti like this:
[url]http://www.overclockers.co.uk/showproduct.php?prodid=GX-248-MS[/url]

And then bought a mobo to support my CPU, would the CPU end up being a bottleneck for the 750ti? Evidently I've not much of a clue what's the best course of action, any help would be greatly appreciated.

[DevulTj]

-did not read title-