Undo of mkfs - urgent

["Manfred Heubach" <heubach@heubach-edv.de>]

Hello,

I've accidently used mkfs.ext3 on the wrong harddisk (used hdb3 instead of hda3). Is there any way to recover the files on this partition? There is no backup copy of this partition.
If it is not possible to recover the files or filesystemstructure maybe it's possible to extract some files from the raw device. Except of running mkfs no data has been written to that disk.
I had 5 zipped tar files (about 800MB each) on this partition. Maybe it's possible to recover at least these files. If tar files all start and end with the same sequence of bytes there should be a chance of finding them on the 20GB HDD. Does anyone no how to identify tarfiles in raw partition data?

Any help is welcome

Regards
Manfred