"RIPE is an international community, and I know that common english
terms can vary widely between different areas.  In the US, the term
'transvestite' is often used as a slur. Transgendered is the widely
accepted nomenclature. I find
http://www.transequality.org/issues/resources/transgender-terminologyto be a good guide for definitions of trans terminology."
You
 are right, it is not easy to get terminology right across borders. But 
this list is USA biased and that is not the same as in the UK for 
example. But in either case 'transvestite' is not the same as 
'transgendered'. From this list 'transvestite' is synonymous with 
'cross-dresser'.
It
 says, in the explanation for cross-dresser, "The older term 
"transvestite" is considered derogatory by many in the United States.". 
That is not the case in the UK. Whilst transvestite (trannie or tranny) 
and cross-dresser (CD) are to some extent interchangeable, they are 
often used in different contexts. In a profile on a personals web site 
you may say "Looking for a CD". But if you went to the gay village in 
Manchester and wanted to find one of the bars where many transvestites 
meet you would ask someone "where is the trannie bar?".
But
 of course these terms constantly evolve and it is a while since I was a
 regular in Manchester....so it may be all different now :)
cheers
denis