Ironworks has a good selection of portraits--go to the Baldur's Gate 2 section, they have the biggest selection (12 pages of 'em). Only a few of them will be Drow, but quite a lot of them are good.
www.kirith.com also has
tons of portraits.
Also, go to
www.google.com and do a search for "Soluafein NPC MOD." I hope I spelled Soluafein right. Anyway, it's a program written by a guy named Westley Weimer, that you can add to your BG2 directory, and it creates a Drow Fighter/Mage NPC, who can join your party. His page has a good selection of Drow portraits that you can use for Soluafein.