[OtherOS] Accidentally overwritten FAT, need to recover partitions!

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http://ubuntuforums.org – Hi guys, I just gave myself a massive heart attack! So I was rejigging the boot sector of a USB device when I identically wiped the wrong drive using fdisk. F*ck. My 320Gb drive is now screwed, it should still contain my windows 7 install, Ubuntu 12.04 install, swap disk and maybe one for grub but Im not too sure how that works. Which tool is best to recover the partitions?? The data is valuable so I cant just reinstall. Also I cant boot into either so I need a bootCD solution if possible. Hope you can help! Thanks Tom (Hardware)