I would definitely say drop Khalid and get Kivan. Kivan is superior in many ways to Khalid and he makes an excellent archer. Try giving him the Bracers of Archery, Longbow of Marksmanship, Arrows of Piercing and look at his THAC0. At level 7, his THAC0 for me with this equipment was 4. Kivan is an excellent addition to any party.
-Jafin
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Arch-Mage of the HADB
Destroyer of the evil Bunnies
Guardian of Boo and best friend of Minsc