Name, Position, Organisation Name and Address (each on a separate line)
Date
Dear (line manager name - eg., Mr Smith, or first name if appropriate)
Please accept this as formal notice of my resignation from the position of (your job title and site/department/division as applicable), with effect from (normally date of the letter or receipt of letter - check your contract - if in doubt refer to date of letter).
In accordance with my contract of employment I am happy to continue to work until (date that your employment ceases according to notice period, calculated from your stated effective date of resignation).
(This part is optional:) While I believe that I am moving for good reasons, I am sorry to leave, and I thank you for your support during my time with the company, which I have found enjoyable and fulfilling.
(And if applicable:) Please let me know the arrangements for handing back equipment, company car, etc, and handing over outstanding work and responsibilities.
Yours sincerely etc.
http://www.businessballs.com/resignationletter ssamples.htm hope this helps
and that was pinched from here...have a look