Lisa, you would probably have to have someone very knowledgeable in IT to take you from Vista to XP. All the drivers, etc, have to be changed. I was going to do that with difficult child's laptop until I discovered everything involved. I can be pretty computer savvy, but I wasn't going to touch that one.
Microsoft Products don't work in Linux, however Linux has their own version of Office. You can open MS files in it, but MS doesn't recognize their files...which is why I would want to keep Windows on my computer and have them both. Linux is more secure and stable than Windows. And it's free.