I've been doing this for years but I'm taking a slightly different approach. With hardware being so cheap...
First, my needs are basic. No huge files or big downloads, mostly text, gathering data and processing it.
Linux Mint 12 by Ethernet cable to modem and Firefox for gathering and forums. Linux Shutter, editors, and side-interests (Bender, Inkscape, Getting Things Gnome, org-mode, Freeplane, prolog), AV, Web Of Trust. No file storage except temporary/daily.
Windows 2K, not connected to the Internet. Wordperfect, Irfanview. Temporary processing and to CD/USB
Laptop XP email, software download, ImageBurn ViaVoice 8 Advanced. No file storage. Save to CD or USB. Occasional Live Linux CD use.
Windows 2K, not connected to modem or Internet. Wordperfect, Photoshop, Imageburn.
Windows 2K, not connected to modem or Internet. Wordperfect, Photoshop.
I removed XP from several boxes and have the licenses but prefer 2K. It serves all of my needs and I know it better.
I'm planning on simplifying further with a box/board with no hard drive for Live CD/USB Linux. I am also watching for developments in small specialized OSes like Puppy for RPi. My wife has Ubuntu on a laptop and we share email accounts on the same ISP. Her start was Pascal, mine was Fortran. We are not Luddites but we do like efficiency.
I have wiped lots of database apps, OneNote, Access, firewalls, AV and file organizing apps and keep going back to basics.