I recently, successfully lowered the size of my SUSE 10 filesystem using resize_reiserfs in Slackware. Now I want to lower the size of the partition that SUSE is on so that I can increase the size of my Slackware partition. Is it possible for qtparted in Knoppix to do this job for me? If not, are there any other graphical programs that can do this?

Okay, if there are no other programs to do this, then how do you resize a partition using cfdisk. I've searched on the web and through documentation, I can't figure out how to resize.

Side comment: as always, be sure to backup any important data prior to attempting to resize partitions

Bump. I still haven't found an answer.

Maybe you should use a better subject line then - this has nothing to do with the filesystem.

I don't trust the GUIs, and have never had my option changed by experience. Go to fdisk, delete the partition, add new. Simple.
Caveats;
- same starting sector (usually means same cylinder these days).
- make sure it's no smaller than what you made the filesystem. Be *very* careful calculating this. Confusion of "marketing" GB (1000*1000*1000) versus true GiB (1024*1024*1024) is one example.
I generally allow a reasonable margin of error - the "insurance" may be wasted, but your data isn't.
Note I haven't done this with reiser (something else I don't trust), but it works for NTFS, so I'd reckon you'll be o.k.

Thanks for the advice, syg00. I think I'm going to delete all the partitions on my drive and start over. I'm going to use ext3 this time (since there is more support).

No need to do that. The entry in the partition table is merely the start and size (extent) of the partition.
By deleting and re-creating as I advised above, you do not affect the data in the partition. Unless of course you make it smaller than the filesystem.
What you have done should allow you release the space as per above. I regularly do it with NTFS on laptops we get at the office.

However, if you are planning on deleting them anyway, I'd suggest you do the resizing to convince yourself it will work.
You might need to do it some time in the future, and will feel much more confident.

Sorry, I haven't really done much partitioning. Are you saying that I can delete the partition and create a new, smaller one where it was before without deleting the filesystem?

Yep - exactly what you want to do.
Sounds scarier than it really is. The partition entry basically says "go look here for a filesystem", and "it's this big" (in sectors).
Basically you just want to convince it it's now smaller, so you can use the released space elsewhere.

Nothing magical at all ...

Works well with shrinking - expanding needs a lot more care (overlapping partitions are not pretty).