Ha that is one of the reasons Im holding off buying mine. No computer table and also waiting for wages (its such a slow crawl to wage day when I want to buy something with the money!)
As for your build:
1) processor is a good choice and highly overclockable. Very future-proof as it has 4 cores instead of 2. SCAN can probably have a good go at overclocking that to 3.8Ghz and that will perform well. I noticed you havent selected overclock option. This is highly recommended - at least 10%. You will see real performance gains for very little money. And the overclock is covered on their warranty.
2) You can save yoursellf LOT of money by going for an ATI 4890 instead of a Geforce 285. Maybe up to £100. The performance is usually about 10-15% less in most games but in some there is actually a small performance advantage (such as GRID and possibly stalker). You said you mostly want to play older games and crysis. The 4890 is ideal there. Plus highly overclockable (careful of your temperatures though).
3) Upgrade your hard drive slightly - at least go for a 750Gb, its only a few pounds more. The F1 is a good hard drive. Fast and reliable. For what you are doing you dont need a raptor or SSD so its a good choice.
4) I was going to ask if you really need that sound card as its another £60 odd pounds. But then I saw you selected a 5.1 system. So probably yes!
Plus 4Gb Ram....hmm its fine at the moment and probably for another year but see if you can add another 2Gb with the money saved from your graphics card. For total future-proofness. Although after saying that, windows 7 isnt a memory hog so you might get by on 4Gb for a few years. Up to you.
Im not too knowledgeable on fans and cases so its best to talk to scan about that.
The build is good overall. Max gaming on up to 1080p on most games