I'm trying to back up the main partition of my laptop so I can reformat it. I'm using kanotix which comes pre-installed with partimage. I've tried the following (partition I want to back up is 15 gb with only about 5 used)
1)Mounting another partition from the drive and saving the image to that, it sits on 0 and doesn't progress, it should have lots of room, I'm compressing it. Its 9 GB in size.
2)Mounting a share from my windows machine via samba (which I can write to, its tested) and There's about 50 or 60 GB free on that drive and saving the image there.

Both times it sits there, and then eventually comes up with an error saying:
Can't read bitmap block 0 from image.

Anyone have any thoughts I've never used this before so any help is appreciated.

[edit] as an alternative plan of attack, could I:
cp the entire partition into a directory on my windows share (ntfs)
repartition the drive
cp the entirety of it back
reinstall grub with kanotix? (I've got a link somewhere I did it with knoppix when it broke on me once)

and have everything be okay, or is that asking way too much?

What filesystem is on the "main partition" on your laptop? You realizie that you cannot image a mounted partition with partimage. Generally, I would use a livecd when doing a partimage backup for this reason. Then you leave the partition you want to image unmounted and mount the partition you want to recieve the image read/write. If the "main partition" is a linux filesystem, I generally don't even bother with partimage but use tar from a livecd to back it up and gzip to compress the tar archive. Partimage has some limitations about the size of the partition that you restore to that tar does not have.
Post back with some more relevant details re what you are trying to do. I would not recommend using partimage to restore to a partition of different size than the original. If it's smaller it won't work at all and if it's bigger the partition will be reported as the same size as the original.

Kanotix is a live CD. The partition isn't mounted either, and its ext3.
I should instead tar the drive and send it across the network and then bring it back that way? Is there anything special I should do when taring?

That's what I would do or you can do it locally if you have the space. Boot up with kanotix, open a console and run:

$ su
<Enter>
# cd <mount point of partition you want to back up>
# tar -cvzf <full path to directory that you want to put the archive on>/<name of archive>.tar.gz .

Note, the trailing period is important in the above command; don't forget it or it won't work. That's what tells tar to recursively back up everything in the current directory on down. Also, you generally need to be root since there are usually files in any distro that are only readable by root; tar will not archive a file that it cannot read. Also, you will have to have write privileges to wherever you are creating the archive and the partition you are backing up should be mounted with at least read privileges. To restore afterwards, boot up with kanotix again, open a console, su to root and run:

# cd <mount point of partition to be restored>
# tar -xvzf <full path to archive directory>/<archive name>.tar.gz

Again, you will have to have write privileges to the partition being restored and at least read privileges on the driectory where the archive is stored.