I partitioned my new drive into two: one 40gig system and one 160gig data.
After installing (anything from win2K to XP, i'm trying 2k3 server and tiring of it) on the system partition, I created my personal login, logged in then out and back in as administrator. I then renamed the personal directory, and mounted the data partition as a new folder as my personal directory. I copied all the default gunk into the new improved personal folder and assigned permissions appropriately.
I logged in as me as all works just fine.
I have no problem with the default location of application data and I can reinstall the system without killing my data.

You could do the same thing for the 'Documents and Settings' folder. (why the hell did they give it that long name??)

You then don't need to worry about 'D:\' in your pathnames and windows apps dont see things any differently.

This doesn't necessarily help you with eudora/TB configs but might help when you reinstall. (isn't 3-4 months a little too often?)