Upgraded the Graphics card this morning, ended up getting this:
Nvidia GeForce6200 (256mb)

Only thing this is missing is a fan on the heat sink. I've got a spare 6cm one which I'm going to try attaching later on this evening, as it's sat @ 52dec C at the minute.
I've also installed a Belkin 802.11g+ Wireless LAN card, another 250gb Samsung Hard Drive, and a 12cm fan at the front of the case to push air out of the front vent.
The PC is running nice and fast now, having a seperate graphics card makes such a big difference. The screen colours are sooo much more vibrant, and runs a lot smoother.