From PCLinuxOShelp Knowledge Base
Checking the MD5sum
ALWAYS run a check sum before you burn that iso file to a CD. This will verify that what you downloaded matches what they expected you to download so that you're not burning junk to the CD.
Running an MD5sum in Linux
If you're in Linux running an md5sum is very easy because the MD5SUM generation program already exists (in just about every distro that is). At a command line just type...
which will return a 32 digit signature. This signature should match the MD5SUM for the ISO that the distribution has provided.
pclinuxos-kde-2010.12.iso 17-Dec-2010 02:57 691M pclinuxos-kde-2010.12.md5sum 17-Dec-2010 03:08 60
Now after downloading CD pclinuxos-kde-2010.12.iso From the command line (console window) run the following:
to which I better get back... 72f39788908f11ccc630bd5bfef2d53e pclinuxos-kde-2010.12.iso
Also you can check it when running K3B.
If it matches, you're good to go......
Running an MD5sum in Windows
If you're in windows, you'll need to download a free MD5sum generation program. You can get one in many places on the web, here are two:
Running one of these programs will return you the same 32 digit signature that you must match against the one given by the server. One of the programs at the two links above works from a DOS prompt (aka Windows command line) and the other is a GUI based program.
In Windows run md5sum.exe pclinuxos-kde-2010.12.iso to which I better get back... 72f39788908f11ccc630bd5bfef2d53e
If it matches, you're good to go and on your way to installing Linux!!
The MD5sum value generated by the ISO that you downloaded MUST match. Don't attempt to burn the ISO to a CD because you'll just frustrate yourself and waste a CDR if the ISO was bad to start with.