If you still need / have invested in MS-only software, and still have the install media for both XP (or 2000) and your installed software, you can install them in a virtual machine running on any Linux distro. Install Linux, then virtualbox (free download from www.virtualbox.org), then install your MS environment into a virtual machine (VM).
Once installed, you can take a snapshot of the VM so that if the VM ever gets corrupted or virus infected, simply blow away the VM with a restore from your snapshot.
Once you're running Linux, have a look through the software repositories and I think you'll be surprised at how much open source (& free!) software there is - the only software I've paid for in the past 5 years is AVPlan on my iPad! At work I have to use Win7, and I find it very frustrating!
There are a LOT of Linux distro's out there - personally I use kubuntu, which is the ubuntu distro with the KDE desktop, as I just couldn't get my head around the Unity desktop which is standard with Ubuntu - too 'Fisher-Price' for me. Linux Mint and Suse are also great distro's.