I've rebuilt it it - I love the smell of a fresh build in the morning! and it's dropped in flawlessly. I tried to build it yesterday with an old disk for the soundcard & the driver blue screened it. That definitely upset the cart. Today I've used the correct driver & it's fine. It really is a palpable step up from the beta versions in terms of speed & feel and let's face it, the beta's weren't bad at all.
I think ms may be getting it right, we'll see.