I've downloaded ubuntu, kubuntu and knoppix from different places and different ways (torrent, download program, browser's download)and each one I download has a different checksum then what is listed on the website.
I've downloaded ubuntu a few times and I've gotten the same checksum each time but it is not the one listed on the site. This is also true with Knoppix.
Anyone tell me what I'm doing wrong?
I'm using windows xp and firefox

Download using a download manager instead of a web browser.

I've used DAP 8. And I continue to get a bad checksum. Since download managers seem to pull from several different places, I wonder if there is more of a possibility of getting a bad checksum.

I have always had bad luck using DAP to download large critical files. The plus is if you lose a connection it will resume, but if it is a bad download it was a waste anyway. I have downloaded a 14 cd set of Debian and roughly fifteen others and never had a problem using XP and going through Firefox. I do have a pretty good DSL connection though.

I have never had any problem using wget in the command line to download iso images. It is also able to resume downloads.
Just do a "wget ftp://url/to/image.iso" and to resume if necessary go to the folder where the partially downloaded file is and start it again with "wget -c ftp://url/to.image.iso".

with Ubuntu of any of it variants unless it doesn't work don't worry about it the problem may be how your computer interprets the files compared to theirs I too noticed when I installed Xubuntu but it went off with out a hitch and works squeaky clean for me. This can happen because of sector size on your hard drive the bigger the sectors the more generalized the actual size of the data will show because even if it only fills some of the sector it will display it as taking the entire sector up like wise the smaller the sectors the more precise it can git about the size of the data.

titopoquito - I'm not sure how that all works...can you give me more details?

Zeriph - so do you think that the files are actually okay they are just reading bad because of sector size?

The best way to know for sure is to burn one and try it. It'll either work, or it won't.

I know of someone whose md5 checker gave false results. Perhaps you should follow these instructions (using the same programs): http://www.openoffice.org/dev_docs/using_md5sums.html

Yes, I have tried them. Knoppix sometimes boots and sometimes doesn't from the Live CD. And Ubuntu only booted once from Live CD. This was after I hit enter or space or something because I was surprised it wasn't working.