I made the switch, and I will never go back to winblows.Reasons:stability, it just plain works, can be setup to do anything, cheap hardware-->no need for anything speedy to get things done,not much worry about viruses or constant patches,its free, its open source.
These days you need a fairly speedy PC to run windows effectively, not so with linux, anything over 5-600mhz w/100mhz bus and 128mb ram and you can do alot.Watch dvd's,surf, do office stuff, it has native top notch networking tools and servers,burn cd's, etc etc.
The only issue I have run into is it can be a little finicky about hardware, especially printers, other than that its all good.