There may be some potential problems with installing sw:
Say, in XP,
you install something with a Batch/Command file that references the Ext drive, which is H:
If the sw is executable under w7, it won't work right (missing files),
because now the Ext drive is G:
situation (install under w7, run from XP) would produce the same kind of results,
due to the "drive renaming".
There could be undesirable
results here, if w7 "writes" to E: Virtual drive
the same pgm executed under XP, writes to E:, which is now E: for Windows XP SP3 x86
Just gotta 'keep an eye out'...
(The old: "Hey, where did it go?", or: "It never did that before!!!")