My Passport 4TB USB 3.0 external drive

I just purchased a My Passport 4TB USB 3.0 drive. If I format this drive on my PC running the Windows XP OS can I then connect this drive to my laptop running the windows 7 OS and be able to transfer files that I had uploaded from the aforementioned Windows XP Ssystem or will the files be incompatible with the windows 7 System?

You shouldn’t need to format anything - just plug it in as it should come pre-formatted with NTFS (presuming you didn’t buy the Mac version). It should work fine with both, although you may need to manually install the drivers on the XP system as I don’t think Windows will do that automatically for you these days as Windows Update doesn’t support XP any more.