I just started Icewind dale 1, I'm in the vale of shadows and my 2 fighters are doing damn near everything. They are just wrecking machines while my mages hide in the back and plink at stuff with their little slings. I think they are only level 4 so it's still early, but they just suck. I blow through their spells way to fast. I'm tempted to delete them and add 2 more fighters or a fighter and a cleric. Or should I just continue babysitting them until they become badasses? (my other party members are a theif and a cleric)

In AD&D mages strart as the weakest characters, being able to cast only a couple of spells per day. But they end up being the most powerful class, especially if they are dual or multi classed. And you will deeply regret not having someone able to cast Fireball when you meet armies of Cold Wights.
One single class mage is enough in Icewind Dale, though.

Mages become very useful at later levels if you use them properly. Against mobs a good tactic is to lay down a few AoE disabling spells (web, grease, etc), then once the mob is tied up in those fire off a few AoE damage spells and have your fighters mop up whatever is left. Spell like confusion can also wreak havoc among an enemy mob, and summons can be quite useful for taking some of the heat off your fighters in tougher battles. Ultimately mages are like artillery- small skirmishes will end quickly enough with or without them, but for bigger battles you really want them around to lay down some hurt.

I still haven't finished quite finished Heart of Winter. My experience is that my magic-users spend most of the time not using magic.

My party has a Transmuter (dual-class from fighter after 3rd level) and a Mage/Thief. The Transmuter has +++ specialization in crossbow and 18 Dex, so does pretty well in battle firing missiles. The Mage/Thief primarily just uses the bow in battle.

Even though they don't use their magic often, it comes in handy in certain situations. Magic Missile- with casting time of 1 and no chance of missing- remains a highly effective means of disrupting enemy spell-casters. Summoning spells are very helpful in those tough battles where you just need to slow down and distract the enemy for a couple of rounds.

So my experience is that mages aren't terribly useful in most battles, but in a few battles they are vital. I don't think they are quite the difference-makers as compared to Baldur's Gate, but it's hard to live without them.

My recommendation is that make sure your mage has something to contribute beyond just spell-casting. The route I went with the Transmuter is one I feel I chose well. In another game, I probably would probably replace the Mage/Thief with a Bard (and still have another dedicated thief in the party).

Cool, thanks for the responses, I'll keep the buggers around. At least I can throw out a few magic missiles with each of them now.

My mage is only level 4 and she is basically a nuke on legs: everything in the Vale of Shadows dies to her Level 2 Agannazar’s Scorcher. Got a boss creature trotting your way? Clear all your other dudes to the sides of the hallway and let her blast once! The downside to this is lots of resting until you get more slots for your spells.

My favorite is having a Druid, Mage, and Bard. Cast Web, Grease, and Spike Growth and watch the hilarity ensue.

mages are a must in parties.as everyone said,they start very weak,but when they reach higher levels they are almost impossible to kill at close range and even ranged attacks,because of protection speels.

This is a game where your wizard will hit level 7 (4th level spells!) about a third of the way in. You'll suffer through the first few areas but a well crafted party can deal with it. They won't have noticeably lower THAC0 at level 1 if using missile weapons and have decent DEX and by the time their poor THAC0 bothers you they have enough spell slots to contribute.

The only real limiter on their power is you will only ever have access to enough scrolls to power 2 arcane casters, be it two wizards or a wizard + a bard. Protecting them is trivial, you should have a stout enough front-line to cover for them and later in the game they'll probably have better protections from self buffs than your front liners will.