You have chosen to play a very difficult but rewarding race in Ultima Online.  Drow are vile, cowardly, unpleasant and manipulative.  They strongly hate humans (rivvil) and in turn are strongly hated by them as well.  Even our closest allies should know that we could turn on them without warning if we find it in the least useful to do so.  You should be prepared to play this part consistently and at all times.  Our "job" in playing evil bastards is to give the good guys something to fret about.  If we do our job right, we are not only having a good time ourselves, but making the game more enjoyable for others as well.
Playing a Dark Elf in Ultima Online
Some useful links to help you get a better idea of how to enhance your role-play as a Drow.
Drow Information (mostly taken from Drow of the Underdark by Ed Greenwood and relates almost entirely to TSR's vision of the Dark Elf)
Drow
Language
Dealing with others (our war list)
Drow Cultural Overview
RPing a Slave
The Darkside of Ultima Online
Drow Pics
Roleplaying 101