A quick google for "md5sum win32" turned up this
http://www.toast442.org/md5/
(I assume you're using some form of MSwin)
Now, to give you more of an idea what md5sum's are about
:
The md5sum is a 'magic' number that represents a sum of the file contents.
From the site that you got the iso's from, there will also be a text file(s) that
contain the md5sums for each iso.
----------------------------------------------------------------------------
eg:
Icon Name Last modified Size Description
[DIR] Parent Directory -
[ ] FC3-i386-SRPMS-disc1.iso 04-Nov-2004 08:41 563M
[ ] FC3-i386-SRPMS-disc2.iso 04-Nov-2004 08:42 563M
[ ] FC3-i386-SRPMS-disc3.iso 04-Nov-2004 08:43 562M
[ ] FC3-i386-SRPMS-disc4.iso 04-Nov-2004 08:45 562M
[ ] FC3-i386-disc1.iso 04-Nov-2004 08:35 617M
[ ] FC3-i386-disc2.iso 04-Nov-2004 08:37 638M
[ ] FC3-i386-disc3.iso 04-Nov-2004 08:38 637M
[ ] FC3-i386-disc4.iso 04-Nov-2004 08:40 386M
[ ] FC3-i386-rescuecd.iso 04-Nov-2004 08:29 76M
[ ] MD5SUM 04-Nov-2004 09:30 791
[ ] README.DVD
----------------------------------------------------------------------------
What you do, is download the iso, and then run the md5sum programme.
Compare the output from that with the number in the MD5SUM file.
If they are equal then your download has been successful.
Once you have burnt the image to cd, you can also use the same technique to
check that the cd has the same md5sum (not sure how to do this in MSwin).
Here are the md5sums for fedora that I got off my isp's mirror:
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
ca49964739f84848ca78fc03662272fb FC3-i386-DVD.iso
e5e0328370d899bd77c8d5c7f1bd3ead FC3-i386-SRPMS-disc1.iso
5cf3f9ae84d8d0ec49679618c9cc2236 FC3-i386-SRPMS-disc2.iso
ee5f134b6880145e576c97c3561cd787 FC3-i386-SRPMS-disc3.iso
7c57d517a6b0bb98b58600392f44ef36 FC3-i386-SRPMS-disc4.iso
db8c7254beeb4f6b891d1ed3f689b412 FC3-i386-disc1.iso
2c11674cf429fe570445afd9d5ff564e FC3-i386-disc2.iso
f88f6ab5947ca41f3cf31db04487279b FC3-i386-disc3.iso
6331c00aa3e8c088cc365eeb7ef230ea FC3-i386-disc4.iso
07bb34ce97b62b99f84d32812a2eec75 FC3-i386-rescuecd.iso
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.0.7 (GNU/Linux)
iD8DBQFBiWL+tEJp0E8qb9IRAtvbAJ9ogGEnoKYeT9exJ/BpO8stFfclAwCfWy6h
iYqa2g5AiQK3PldULLM0Zhw=
=gMjQ
-----END PGP SIGNATURE-----
So, if you run md5sum on FC3-i386-disc1.iso, the output should be db8c7254beeb4f6b891d1ed3f689b412
If it is not, your download is broken and you should download again.