Well, I'm actually thinking of swearing off giving advice on hardware & software!
So, all I'll mention is what I have. A Dell XPS 15, Win7 Pro 64 bit, I7 quad core, 6Gb memory, 750G drive but only two USBs. I use one USB for the camera and mount (powered hub and active cables) and the other for Robofocus and Maxdome.
I went for a fairly high spec because I upgraded to TheSkyX and CCDAP5 and didn't want things to grind to a halt with CPU overload. Last night was the first time I did a full observatory test and it came through with flying colours. I also want to run CS5 and CCDStack on it (both of these use multi threading I believe).
The only real advice I'd give Paul is to plan for the future (= quad core and plenty of RAM - I don't think 1G is enough frankly).
Cheers, Marcus