My question involves landlord-tenant law in the State of: Massachusetts

Hi,
My lease expires on August 31, 2009. I recently emailed my landlord to renew my lease for another year, and he said he would mail the extension form out to me asap.
Now, I've found an apartment close to work, perfect location, available from September.
My question is, can I back out of the commitment with my landlord given that I have not signed the lease renewal yet? There are 60 days left till my lease ends. Can the landlord keep all or part of the security deposit or claim any other dues from me as a result of doing so?
I would be grateful if anyone could help.