Actualy, MD5 can be decrypted...it has only recently been found out though.
I wont post code up here that will prove this as i wouldnt want to create security problems for anyone, however i can assure you - MD5 is very decryptable...i have been able to decrypt upto 10 chars so far, and im sure others have got furthur.
I would appreciate it if people stopped PMing me asking for the code...regardless of your reasoning, i would prefer not to release it.
You can find it the same way i did...
www.google.com