That said, the company I work for has an IT department that is not happy at all to issue non-windows boxes for employees. You can have one, but then you will have to manage it yourself. We have a couple Windows servers but all our software run on *nix-ish boxes.
At least I could install cygwin and X on top of XP.
You say that like it's a bad thing ...
Believe-me, I have meditated on this more than once.
As far a sharepoint goes I don't have any real experience with it but it looks like you are able to use it on linux but the activex controls will not work(of course):
Had I sufficient memory (machine has 1 GB of RAM), I would go down the VirtualBox/VMWare route.
When I switched to OS X from a Windows workstation at my job, I used VMWare Converter to convert my workstation to a VM and it worked flawlessly.
This is what PG described as "Microsoft is dead".
My feeling is that a lot of science jobs will rely on the Linux/Unix platform. Backend or system control type things are on Linux and a lot of personal computers are OS X.