Sometime after 24/11/08 I installed about 4 vista updates, after which boot and shutdown times greatly increased. By which I mean, when you get the green sliding bar when booting, pre-update I would get between 6 and 11 bar progressions, after update I got 50 to 51, before completing the boot.
I've now turned off updates completely and system restored back pre- 24/11/08, and alls well again.
From looking at these forums it seems I am not along with update issues.
I'll leave updates turned off I think.