Differences in MSO versions

[cm7900]

Hello

Can someone explain me the diference between all MSO 2007 versions. I was using this entry from Wikipedia without luck:

http://en.wikipedia.org/wiki/Microsoft_Office

The Wikipedia page don't tell were is MS Visio and MS Proyect. I need MS Visio and MS Proyect, were can i find both in the cheapest version?

Edited April 3, 2008 by cm7900