First of all, Drizzt is weak as hell. For all the genius and effort poured into the sample NPCs in the DMG, the fighters are at least capable of chewing up and spitting out Drizzts. A character with PC wealth of the appropriate levels should beat him. I'd figure that a party of 4 would have decent chance at levels 10-11.
What would happen if someone killed him? Probably not too much. Drizzt's primary allies have similar skills to his - they might even be useful for a dress rehersal for the attack on Drizzt. Also, they have little mobility or information gathering ability. Recently, he seems to have had relatively little contact with secondary allies/contacts. While Alustriel and Cadderly are powerful and might take in interest in Drizzt's fate, they're also busy and unlikely to take notice.
If you kill Drizzt, hide the body, and make sure no one living knows about you should do okay. It'd be just like killing anyone else, but with the added difficulty that he (and maybe his friends) will fight back effectively.
However, thus far Drizzt has only messed with the Drow. He already killed the human thieves guild that messed with his friends. No one misses them. Since he often confronts uncivilized monsters, he even helps evil groups that want to have places left to take over. He's not a significant threat against a magic oriented foe - and the most dangerous enemies of Faerun are magical. It wouldn't be worth the effort.