External Drive not working now !

I have a USB 2.0 HDD EXTERNAL DRIVE (80 GB) , i used to use it with XP.
NOW i have a new laptop with vista basic , it worked well for some time but now it does not work!
I CANNOT see it on the ‘computer’ page, where all drives are .
I have very important data in it
what can i do apart from giving it to a data recovery company ?

PLEASE HELP !
CHEERS