vista has issues im sure even MS would admit that. they've only released it for just under a year and they have a service pack for it already. how long was the XP service pack.. pretty much double that two-ish years now tell me which was better when they were released?
im sure vista will be really good once the creases have been ironed out and i will deffinatley get it once i upgrade my computer with SP1 - but untill then XP works fine, there is no need to upgrade yet.
MS said that they predicted that X amount of units will be sold - how did they come up with that? alot of people arnt going to upgrade an OS for the fun of it - they'll do it when they have to or when there getting a new PC. this is from the view point that not everyone in the world knows how to use a PC, those that can only just get by using one, use it to check email and read the news - why would they want to go through the hassle of upgrading when everything works fine as it is.
if something isnt broke dont fix it!