On windows use
Unzip and launch md5.exe
Copy the MD5 hash sum of the rom you downloaded to your clipboard
Hit the paste button in the MD5.exe program
Browse to the file you downloaded
If the codes match the box goes green and the text tells you that the codes match.
cd Downloads (assuming Downloads is the path of the file)
Check the output of the md5sum command against the has posted in the thread. Also note that the md5sum command on Linux doesn't like special characters such as () / or anything in the rom name. You can rename a file without changing the MD5 hash, so keep this in mind.