Personally, I never buy an off-the-shelf pc. I always build my own, but then I'm fussy!
The deals that have been highlighted do look good though for someone looking for a ready-made pc.
The one I've just built has Vista Ultimate installed now and I have to say it's the easiest Windows OS installation I've ever had. It was all installed and running in about 10 minutes. Mind you, the machine is lightning quick with a quad core processor running at aroung 4ghz and 4Mb of 9200 DDR2 RAM and a Tb of storage in a striped RAID configuration
I've had no driver compatibility problems and no problems running any software on it either, so it's all good from my point of view.
I concur with Neil. It seems if they use one of the big carriers, you will get hit for duties every time. If they use the standard postal service, although this takes longer for delivery, I've never been hit so far.