Thanks guys, great answers! Wow, what a headache. This bit sounded promising:
"Foreigners without a permanent residence visa may import used household goods and personal effects on a temporary basis. One air and one sea shipment allowed. Shipment must arrive within six months after customer or three months before."
And how do you prove the items are not new and have been in your possession for over a year? By having original receipts for all the individual items? Jeez!
So is it really expensive to buy things like computers and monitors etc in Argentina? That makes up a lot of what I would be shipping. (And guitars... he he!)