All good advice. If you're thinking about adding a second graphics card at some point for SLI (nvidia) you will need to set yourself up for this from the start by buying the necessary kit to support this.
Namely, the mobo and the PSU will need to be 'SLI-Ready'. For more info, get the low down from the horse's mouth at www.slizone.com (a website operated by nvidia).
I'm in the process of speccing a new system at the moment too. Now that AMD's AM2 technology has launched, I'm going to go with that in order to 'future-proof' the purchase as far as possible. Scan have already got a handful of mobos but no CPUs in stock to date. Hopefully, it won't be long and the prices won't increase.