Self Employed, very much under $80,000-which IRS forms?

Hi:
I am a US citizen, have been living in the UK the past 2 years, married to a Brit, so I plan on staying...  In 2004, I  had a 100% UK based self-employed income of 6500 pounds.  I will be paying taxes on this in the UK and have been paying National Insurance contributions since I became self-employed.  Anyone have any idea which forms I need to complete for the IRS?  Do I owe self-employment taxes even though I pay self-employment taxes here in the UK?
Thanks!
Ginger

p.s.  modified as I've now done some internet research and have uncovered something called the "Totalization Agreement" which seems to suggest (at least to me) that I should only be paying NI, not Social Security taxes (which is what self-employment tax is, no?). 
http://www.ssa.gov/international/Agreement_Pamphlets/uk.html#certificate2