As a matter of fact I have booted to PCs with the exact same specs , one with Vista and one with XP. The Vista machine booted to a usable desktop in just under two mins. The XP machine booted in 43 sec. ShUt down times were 11 sec for XP and about 6 mins for Vista.

syphus
" Can you honestly rule out the possibility that your experiences with Vista are either coloured by your disappointment with the OS"

Some of it might be that. I am very disappointed in Vista, it was hyped to be so much more than XP and in reality from what I have seen and tests I have done it does not even come close to matching XP.