Found a bargain on the HotUKDeals forums for a graphics card that will do for me, an ATi Radeon X700 for £16.43 ($34.33USD, €23.40EUR).
Although I don’t have Guitar Hero II for the Xbox 360 and therefore, no guitar controller, I downloaded the Guitar Hero III demo anyway and got rather hooked on it, so I’ve also ordered the PS2 version of Guitar Hero II with guitar controller which was fairly cheap (cheapest on the net after quite a search).
I have to use the pad to play the demo, but it’s not that bad and I’m fairly good at the songs on easy, medium is a bit harder due to needing to use the blue fret and it gets a bit confusing, I like it though and I might even get GHIII for the PS2!