Freezes up with the XP screen and the little blue things running across the screen.
If the "things" are pixels or such across most or all of the screen that points to the video system.
If the "things" are the "Knight Rider" panning blocks XP always displays when booting then it doesn't point to the video system.
At a friend's suggestion we installed a new copy of Windwoes in a new directory and it boots fine, but of course is naked and dosn't even see the second montior.
If you *did* install a driver for your video system and the second display wasn't seen then that may point to the video system.
If you *didn't* install a video driver then not seeing the second display is reasonable.
Make sure the fans are turning and that there isn't a lot of dust in the computer.
Just keep in mind RAID is not backup. My description is that backup makes sure good data is available somewhere (even if recovery is a nuisance) whereas RAID makes sure your trashed files are always immediately available. Entirely different goals. Arrange good backup first, then worry about RAID after backup is solved.
You realize that running everything from an external disk provides no benefit and just makes the system slower since your now reading all your data though a (slower) usb connection.
My MacBook Pro runs faster with an external 1394b disk than the internal disk. Any eSATA connector ought to be as fast with an external disk as any internal disk.
Also the general description of the trouble seems to include both the normal, appalling but normal, deterioration of Windows over time
I call this deterioration "barnacles" - Windows updates over Windows patches etc, add-ons like Flash accumulating over time, multiple printer drivers, etc. Any Windows system accumulates barnacles over time which makes it slower as time goes by, causing little failures that grow until it doesn't work at all any more.