I definitely favour dual wielding. Enchants 'cross charge' - e.g. put +100 magic damage and +100 physical damage on both your dual-wield weapons, and EACH weapon will get all the bonuses: +200 physical and +200 magic on each weapon, or +800 damage bonus in total across both weapons and damage types. Dual wielding effectively doubles the value of each +damage enchant, and it doesn't even matter which weapon the enchant's been cast on!
And if you're playing a caster, dual wield with +magic damage on both weapons is the only way to go (in this case you don't need to put any skill into dual wield, as there is no 'off hand' penalty for spell damage bonuses).