Just some of the multitude and ever growing reasons not to use Vista.

IBM will not use Windows Vista - but will move to Linux desktops
http://www.neoseeker.com/news/story/5436/

Becta report slams Microsoft academic licensing, dismisses Vista
http://www.businessreviewonline.com/os/archives/2007/01/becta_report_sl.html

Government agency tells schools to shun Vista
http://news.zdnet.co.uk/software/0,1000000121,39285414,00.htm

Long list of Vista bugs
http://blogs.zdnet.com/Ou/?p=402

Vista is not an option
http://www.theinquirer.net/default.aspx?article=36653

For a whole lot more visit
http://badvista.fsf.org/