I was wondering, which NPC's are keepers and which are throw aways...So far the thieves suck...I can't steal a thing!!!

Should I get rid of Jahiera?

well my personal believe is that multi class character are useless as they will fall behind in level to much

Jaheira's good. Her druid levels zoom up, and she gets Iron Skins in no time, at which point she becomes great for tanking. There's nothing wrong with multiclass NPCs. If anything, the dual classed NPCs in this game are bad. Yoshimo is probably the best thief you can get. Second to him I'd take Jan. Nalia sucks - she can't even pick the locks in her own keep - Imoen isn't too great either. Start a multiplayer game and make your own thief, that's my advice.

The two most overrated NPCs in the game are HaerDalis and Cernd. If you want to check them out get them EARLY in the game where they can at least add some minimal value to your group. At the end part of the game they are basically using up oxygen that your character could be breathing.

BUT...best to find out for yourself, hey?

As the others have said it is down to your own tastes but I'm playing the game for the third time now so I'll give you some ideas. As Armisael says there aren't any really good 'thieves' so if you want one make it youself. This is what I did for this go. I do very little sneaking around, generally being a pretty unsubtle player, so I stuck all my theives points into pick pocketing and opening locks. Needless to say I am very rich already. I stole and repeatedly sold back 50 000 gold worth of stuff from Maevars shop keeper in one sitting. The only store I buy items from is the Adventurers mart because I have to. Make him a swashbuckler. The combat bonuses more than counteract the lack of backstab multiplier. Back to NPCS (after my huge ramble) I took Minsc and jahiera for personality more than anything else and the fact that this seems like what you would do in real life, they're central to the plot. They're both also very good fighters. Jahiera is actually one of the few npcs that can carry a shield. The other two characters I took are Viconia for lots of extra healing and she fights really well too once you give her the mace maulers arm and Aerie for my mage and even more healing. All the other wizards excepting Edwin are thief/mages and I don't need a second thief. I only have five characters because I figured there's no point wasting experience on a character that I'm only going to dump when I rescue Imoen. Imoen may be a bit crap but I'm not going to leave that poor innocent girl behind after going to all the trouble to rescue her. Well there's my about five dollars worth!!