"When plugged into an XP machine it loads as an internal drive - not an external device"
That's not possible, so you're misunderstanding something. What makes you think this is so?
The easiest way might be to connect this drive to the XP machine, share it, then open it on the Vista machine.
hughv
Veteran Poster
1,142 posts since Oct 2007
Reputation Points: 116
Solved Threads: 93
"Loading/installation? Are you sure that's not just the Autorun feature?
Right-click this drive in My Computer and select "Explore".
You mentioned an XP machine, so I assumed you had two computers available.
You can try exploring from disk management as well.
hughv
Veteran Poster
1,142 posts since Oct 2007
Reputation Points: 116
Solved Threads: 93