After two months of intense research i've finally got all the bits for my new PC. I'll be finishing off putting it all together this evening and then flicking the power switch for the first time.
Many thanks to everyone on this forum. Many of you have helped in the decision-making process for the new rig. I'm also over-budget by £600 thanks to you lot, so i'll be living off bread and water for a few months! My original budget was around £1000. This was for a 'medium-spec' PC (6600GT, 3200 A64).
I used the following retailers to source my components: Scan, Komplett, MicroDirect, Tekheads, Dorothy Bradbury and Dabs. In terms of quality of service (ordering process, delivery, customer service) Komplett, MicroDirect, Tekheads and Dorothy Bradbury were exceptional (Dorothy Bradbury was by far the best of the lot - amazing how a small E-Bay outfit can compete with multi-million pound companies and deliver a much better quality of customer service). Scan was good but did have significant shipping problems early on that have started to improve in recent days. Dabs were really poor but I got a cracking deal on 1GB (2x512MB) Corsair TwinX 3200-XLPT from them.
My sig shows what I ended up with at a cost of around £1600. A fair old hike in cost but quite a bit more powerful as well. I reckon I ended up paying around £50-£70 in postage costs as I bought the kit in drabs and drabs. But I reckon I saved over £120 by shopping around. So, the net saving to buying all the parts in one go was around £50-£70.