I think the HTPC is ready to go! Finally. It's been a long road, largely because I like fiddling and want everything just right. I've worked my way through Vista, XP and onto Windows 7. Now it all works. It is not perfect (for instance, Media Browser is rather slow to start, I could fix that with a ramdisk but that just adds complexity to the solution hence more things to fail) but it is usable by normal people.
Finally have all my move information up to date, Mediabrowser is a great product and when coupled with Media Center Master to get movie information works well. Incidentally, I installed the latter on a different machine so I can control updates and avoid extra software on the media centre machine.
Happy? No, now I want to put it into a smaller box (disappointingly the dual core atoms are still a little lacking and I would already need to have two 640Gb laptop drives so getting costly and limiting on hardware). I also want a mini wireless keyboard with built in mouse / trackball but don't want to pay £30 for one - I'll test the remote more and see how we get on without.