Some times you download large files and you might want to verify the integrity of the file, or it could be that you are the distrustful type and simply want to verify the file integrity just because you can!?
MD5 is an older check-summing algorithm, basically you put data through this algorithm and it spits out a long check-sum – change as much as a comma in the file or text and the check-sum changes. MD5 is no longer considered ‘safe’ as some vulnerabilities have been discovered, however it would still be complicated to ‘fake’ the right check-sum for a file – so for something as trivial as file check-summing I would consider MD5 safe enough – then again it depends what are you looking for corruption errors or deliberate attempts of tampering (for the latter you should perhaps go with SHA1 instead).
Fine, so you got the MD5 check-sum (eg. 73f48840b60ab6da68b03acd322445ee) from the website, how do you compare it to the file you just downloaded?
Well I found this util which is free and fairly easy to use.
http://www.winmd5.com/?rid=winmd5