I do it all the time, I tend to have 3 different OS installed in one hdd. I use GParted to delete, create and resize partitions. Though I never leave important data on the same harddrive. Edit: Actually now that I think about it, Windows Vista and 7's Disk Management has shrinking feature that can resize your partition. You can just use that. The GParted way: For the 1st hdd, you can use GParted to delete the Windows partition, then resize the 90% partition back to 100%. The thing is if you resize a partition and files within the partition has to be moved across the hdd aswell, then the resizing process will takes a very long time with 1.5TB of datas. Because if XP partition was to the left and got deleted, the 90% partition is expanding itself to the left, GParted also will move all files within the partition to the left. For the 2nd hdd, you can shrink it and leave 100gb of free space in the end of the hdd, then create a new partition out of that free space.