Is there a way to change the default destination drive in Windows XP
so that when you install a program you don't have to click "Change",
it just goes to the other drive?

Sure.  Go to

http://www.microsoft.com/windowsxp/pro/downloads/powertoys.asp

and download TweakUI for Windows XP.  Install and run it.  Then
navigate (on the left side of the program window) to My Computer >
Special Folders, and pick the folder "Programs" in the drop-down
listbox at top right (the default is C:\My Programs\).  Click on
"Change Location," and you should be in business.

You could probably manage the same effect by using regedit (Start >
Run... > regedit.exe), but TweakUI gives you a nice front-end.

(BTW, if this answers your question, please close the question and
save your $3.50.  A few months back, I asked a question and had it
answered in a comment, then someone else came along and put the same
information in the official box, "earning" the money.  Since I wasn't
approved to officially answer questions, you won't hurt my feelings by
closing the question. :-))

Also look in to Active X controls (.OCX files).  I use them in DB
development to lock people out of saving to local hardrives.  I am
sure they are easliy used in the same way for windows.

Thanks. :)