Its is most likely an ownership issue as the XP drive is NTFS.
This solution is for XP, but the steps are the same in Vista.
http://support.microsoft.com/kb/308421
--
David Vair
CNE, CNA, MCP, A+, N+
"Krakapo" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
>
> All - XP PC died, taken the hard drive and placed into external USB cage
> and plugged into Vista laptop. I cannot see it in My computer but under
> disk management I can see it as a disk and a healthy operating
> partition, but it has no drive letter and I am unable to change the
> drive letter as the only option I have is the delete command. My
> presumption is that as this was the master boot record on my XP PC, this
> is the reason why I cannot change the drive letter? But I am unsure.
>
> I have 90% of the data backed up on a seperate USB drive, but it's the
> 10% especially some recent video and photos that I want off the drive.
>
>
> --
> Krakapo