Hard drive not reading

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http://ubuntuforums.org – I was working with XP Pro os and it chrashed. Moved to ubuntu 11.04 and moved the XP Pro hard drive to the ubuntu system. HD worked just fine. This HD was a boot drive for XP Pro. Purchased Win 7 system moved the XP Pro hard drive to the Win 7 however, win 7 does not reconized the format on the hard drive and wants to reformat. Currently there is data I would like to keep on the hard drive. I moved the HD back to the ubuntu system and I am unable to see the data on the drive. I remember when I first hooked the HD to the ubuntu system it gave me a message about the formate type of the HD an (Hardware)