koolstacy,
Are you in the US? If so, the laws on SRS and pre-existing marriages very from state to state. It will also depend on what documents you choose to change (birth certificate and social security, mostly).
My understanding is that at the federal level, if you change your gender on all of your documents, you cannot legally be recognized as married (i.e., file join taxes, enjoy social security benefits, etc) due to DOMA; however, I also understand that this has never been (and likely will never be) challenged in a higher court of law.
Someone feel free to correct me if I'm wrong.
~Jas