Problems Transferring Data from External HD

Hello,

I bought a new computer (Windows 7) and took my old computer hard drive (windows XP) and put it in a Sabrent Enclosure to transfer files to the new computer. New computer recognizes the drive as "K" drive but tells me I must format K-drive before I can use it.

If I format the old drive I will loose all of the data. What can I do to get my new computer to recognize the data on the old hard drive. It's driving me crazy.

Thanks