Windows 7: Windows 7 recongizes usb but doesn't see XP files

I have files backed up on a WD My Book external hard drive from my XP computer. I plug in the USB in my new HP Touchsmart, it opens the jump drive, but says the folder is empty.
I also have files on my PNY jump drive from the XP and another Vista computer. It opens the jump drive and sees the Vista files but not the XP files. The Vista computer sees all files on the WD My Book and the PNY jump drive. Any suggestion to get Windows 7 to see the files.

In every thread I have seen, Windows 7 doesn't see the Jump drive at all.

whats the xp drive formatted in?

I was told it's fat 32. I'm not sure how to check it.