I know that a character starts with a free set of clothing of 10 gp value or less but I seem to recall (quite possibly erroneously so) that the clothing one wears does not count towards encumbrance.
All weight counts towards your encumbrance. I believe what you are remembering comes from 2nd Edition most likely as I also recall a similar rule... which I can find no trace of in 3e based books.
Clothes do count for encumbrance in Pathfinder. 1 1/2years ago Jason Bulmann did clarify this in a thread that I had started. Too late here to search myself - but it has been clarified.