Given what you've said above, and setting aside the spiked chain portion of the concept, you might consider some of the following tweaks to boost your mage's use of force effects. Force effects should be effective against most undead, especially the incorporeal ones.
So...assuming you stick with Wizard as the PC's primary class.
1) Be human, you'll need the extra feats. Also, stick with making him a Wizard, he'll get those useful bonus feats (more on that later)
2) Consider making him a Specialist Evoker or Abjuror with the Focused Specialist ACF (Alternative Class Feature) from CompMage, p34. That will get him nearly as many spells/day as a Sorcerer.
3) Take the Intermediate Magic ACF (PHB2, p68-70) appropriate to the PC's specialization- in exchange for giving up the Familiar, the first gives Shield of Force +2AC and the latter gives the Counterfire force bolt.
4) Use your Human and Wizard bonus feats to take Invisible Needle (gives you an at-will force bolt as long as you've memorized an appropriately powerful force spell) and Blade of Force (sheathes your melee weapon with force energy as long as you've memorized an appropriately powerful force spell). (As reserve feats, they qualify as metamagic feats.)
For overall utility, check out this list of arcane Force spells that I know of in the PHB, CompMage, CompArc, and PHB2 (I'm sure there are more):
Lvl 0 ?
Lvl 1 Bigby's ______, Mage Armor, Shield, Ectoplasmic Armor, Magic Missile, Orb of Force (lesser)
Lvl 2 Bigby's ______, Blast of Force, Force Ladder
Lvl 3 Chain Missile, Mage Armor (Greater), Mage Armor (Mass), Repelling Shield
Lvl 4 Bigby's ______, Force Chest, Force Claw, Force Missiles, Force WArd, Force Wave, Orb of Force
Lvl 5 Bigby's ______,
Lvl 6 Bigby's ______,
Lvl 7 Bigby's ______,
Lvl 8 Bigby's ______,
Lvl 9 Bigby's ______,
5) Take 1-2 levels of fighter in order to get the bonus feats for Spiked chain proficiency and/or the feats you'd need to fire into combat.
6) All that notwithstanding, you might also consider going the WarMage (CompArc) or Battle Sorc (Unearthed Arc) route so you can cast in armor- the latter also gives you proficiency in a single one-handed martial weapon. And of course, being an Elf would get you some martial weapons proficiencies as well, at the cost of that Human bonus feat.
I know, its not the spiked chain, but...