Restore ipad not enough space

Hi,

I made an itunes backup of my ipad, but now itunes doesn't want to restore it!

I always get an error saying it couldn't restore, because there isn't enough space available on the COMPUTER.

The computer I backed the ipad up to, has a 40gb hdd. The backup is about 20gb. I think itunes first makes temporary files in order to restore. But i can't manage to get enough space free, i have about 10gb free.

I tried putting it on an external hdd to restore on another computer, but it always says it couldn't copy some of the files. The drive i used is fat32. Could that be the problem, altough when looking through the backup, there isn't any file bigger than 3gb? I'm trying to get an ntfs drive and see if i can copy it to that drive. If not, how can i recover my files?

Thanks in advance, and sorry for the bad english.