I've never soloed the game with a Wizard or a Sorcerer, so I can't tell you which one is best. There are some things you should keep in mind, though.
First of all, there are racial restrictions on the classes. For example, if you choose to play an elf for the +1 DEX bonus, you can only play a Diviner, an Enchanter, or a non-specialist Mage. If you wanted to play a Conjurer, you'd have to play a half-elf or a human, and you couldn't get the racial DEX bonus. This will help you to determine which class and race to select.
Any item that can increase the number of spells you can memorize is very helpful (Ring of Wizardry, etc.). So is any item that can decrease casting time (Amulet of Power, Robe of Vecna). Also, check out Improved Alacrity (one of the High Level Abilities). And speaking of High Level Abilities, some of them give you the ability to cast extra spells, while others give you the ability to cast awesome spells, so choose them carefully.
I agree with Raumoheru--the Bracers of Defense and the Robe of Vecna should be your first picks for armor. (Pick up Yoshimo or Jan and go on a shoplifting spree if you're worried about gold.)

But instead of relying solely on armor for protection, you should also use the protection spells that are available to you. Stoneskin, Mirror Image, Invisibility, Mislead, Protection from Normal Weapons, Protection from Magical Weapons, Protection from Fire (and so forth), Project Image, etc. will give you better protection than any armor. To prevent them from being dispelled, you can combine them with Spell Immunity: Abjuration, Spell Immunity: Divination, and so forth.
As for weapons, the Staff of the Magi is considered to the best choice by most people. I wouldn't try to hit anybody with it, though; I'd wield it just for the beneficial effects (Invisibility, various Protections, etc.)
Instead of relying on weapons, which can't usually do much damage in the hands of a spellcaster, I suggest that you rely on summoned help to do your melee fighting for you. There are all sorts of options in the game. You can get a Wand of Monster Summoning early in the game. Animate Dead and Mordenkainen's Sword are two of my favorites. Later in the game, when you're really high in level, you can use Project Image several times and summon several Planetars. If you can do that, does it matter if you're holding a little dagger or a wimpy sling?

Just be careful when you fight monsters that can cast the Death spell, which will instantly destroy most summoned monsters.
In addition to summoned help, you can also recruit an NPC temporarily if you need help with a particularly tough quest. For example, when Keldorn is sent to help you on the Temple's quest, you might take him up on it. When the quest is over, you can dismiss him. If you need the skills of a Thief, let Yoshimo help you for a while. Just because you let someone into your party, that doesn't mean you have to keep them forever. There are some places in the game where I'd rather not be without a Thief or a good sword hand. But if you can get by without them, then don't take them with you.
Your best offense, of course--better than any weapon you can hold in your hand--is your arsenal of spells. The really powerful spells such as Horrid Wilting, Finger of Death, and the good old Fireball are very handy, of course. But don't overlook the lower level spells! Magic Missiles are devastating if you hit an enemy with enough of them. Chromatic Orb was my favorite spell when I played Icewind Dale because it can stun the target. Grease and Horror will keep large groups of enemies from swarming you. Spook will also keep an enemy away from you. Glitterdust will seriously weaken your opponents. And those are all just 1st and 2nd Level spells.

Lower Resistance and Greater Malison are essential when you fight enemies with high magic resistance or low saving throws. If you want to set "traps", use Skull Trap, or lob it like a hand grenade towards thy foe.

And then there are High Level Abilities such as Dragon's Breath. "Which weapon should you use?" I'll let you decide.
I hate to say it, but if you have primarily concentrated on melee attacks in the past (which is incredibly fun--don't get me wrong), then you can't really know what to expect when you play a game that concentrates primarily on spellcasting. You'll need to study the spells very carefully and learn how to use them for best effect. I'm sure you'll get a lot of useful tips from people here. Pay close attention--it's worth it.
