XP would format it with an MBR and probably using 512 size sectors. W7 maybe formats it as GPT disc with 4096 size sectors. XP wouldn't read the GPT format disc, but W7 should have been backward compatible to read the older MBR 512 size sector format.
I have an IOCELL external hard drive that I use to back up data from all my home computers. It works fine with Windows XP systems but with windows 7 It gives me the error ' you need to format drive f....' If I access it from a windows XP system at the same time, it works fine. In order to fix the issue on Windows 7 computer, I copied all the data on the external hard drive to my xp computer and then from Windows 7 computer, I reformatted it. After reformat, the drive was visible from Windows 7 computer but then I started getting the same message from Windows xp computer. I have gone back an forth between the two computers but have not resolved the issue, Can someone help? Thanks.