Oooh, I think I see what happened. I'm guessing there's already a partition on the drive you're trying to use? It's probably looking at the drive and either seeing 2GB that it can work with (ie, unpartitioned), or looking at the partition, deciding that it can only shrink it 2GB, and telling you that. If you're wanting to wipe the drive, you'll have to select the partition, tell it to delete it, then select the new empty space, and tell it to make a new partition. If you want to shrink the partition, it's obviously not reading it correctly; I'd recommend the GPartEd Live-CD to shrink the partition, then boot back into the 7 install and have it use the empty space.