Provided there is sufficient memory, VMWare can be very useful for supporting multiple OSs.
http://www.vmware.com/ You can run Linux as the base OS, with all your regular apps, and then when you need to start up one of your windows apps, you just open a VMWare virtual machine session to boot copy of Windows XP/2000/2003/98 or whatever, and carry on as normal. The windows session can either run in full-screen mode or in a regular X-11 window under KDE/Gnome/some other window manager.
I have just installed six big linux servers at work which support three Windows 2003 test environments each, and they have been running like a dream. I wrote a few Perl scripts that control the Windows environments automatically (take down any of the environments, replace it with a clean one from a baseline archive, reset the Windows machine names etc, kick off the installation of prerequisite software eg SQL server, tar it back up, and deploy it on any of the physical machines). It is *far* easier than trying to do backups with Ghost and so on, and it has saved buying and installing a lot of extra hardware.