External hard drive issues! Please help?

I have an external hard drive in a cradle. It works fine at home but I just brought it over to my gf's place and now I can't get it to read. I know whenever I restart my computer at home I have to reactivate it in disk management but when I open up disk management here it comes up as foreign. The only option it gives is to convert to basic disc, which it says will erase data. Am I missing something? Do I need some sort of driver or something? And if so, can I download one? Only other thing is I don't know all the specs of the hard drive or cradle, is there a way of finding out? Any help would be much appreciated.

 

What operating system are you and your gf using? It could be the disk is formated in a file type the other computer does not recognize.

E

 

They're both XP