Downgrade my Toshiba from Vista Home Pre...

I have just been having too many issues with my software, many of them don't have fixes for Vista, some had fixes and don't offer them any more because they didn't work. My machines can't seem to remember settings for some of my programs and 6 our of every 10 start-ups I get a message that a program has started a thread that belongs to another program, etc, etc, you must used Launch repair (or something like that) to fix it or ty starting windows normally. Of course if ou try that, it never works, but then neither does the Launch Repair more times that it does. Registry is always saying to delete all temporary files, that fixes things for a little while. I could go on "ad-nauseum". I understand that doing the down-grade can cause some of the hardware to stop working but I also understand that other, XP software can be downloaded to fix the Wireless and th Web Cam, etc.