While Linux is somewhat dangling on a rope (the kernell is now kept by a 19 year old brazillian kid), it is much more stable and trustworthy than any windows platform IF you know what you are doing. Unfortunally most of us don't, so I say, get Win2003 and a 10 year old, and you got yourself a good database server, or web server, or network gateway, or whatever.

Regarding speed, you would be amazed by what a computer with Linux can do... That's when you realize how FAST a 2ghz processor really is.

Solaris, to me, is for educational porpouses only, sort of like an educative toy. It's great but very unstable. I wouldn't have a critical process running on a Solaris. But if you want to learn Java, it's great to sit in front of those cute SUN terminals and code on those... You won't need to install a virtual machine anyway!