After using Windows Vista for over a year now, I took the dive and installed Windows Server 2008 on my Fujitsu-Siemens Lifebook E-8310 laptop. So far a great experience: all my Vista drivers work like a charm and almost all applications are working. What I really like is the modular approach on this OS: you only install what you use. Performance is at least on par with Vista, sometimes I think it is even faster.
I'm definitely not the only one doing this: Installing Windows Server 2008 on a Laptop “Installing Windows Server 2008 on a Laptop”) And if you want a nice step-by-step on how to set this up go and see here.