Electrum is easier. Armory is harder. Electrum lean towards minimalism. Armory is aimed at power users.
Even though you asked about offline wallets you will likely want to maintain a watch only version of your wallet on your online system to be able to see the current balance, create unsigned transactions and give out addresses to people who want to send you money. So let's compare the online wallet experiences as well.
Armory's online wallet requires a copy of bitcoin-qt running and that means you need to download the whole blockchain. Armory's online wallet is also known for being a memory hog. The advantage is that you have a local copy of the blockchain and don't have to trust anybody else with that.
Electrum relies on third party servers so it runs pretty lean. The downside is that you loose out on privacy to those servers and if they are compromised they could send you fake transaction data and not broadcast your send transactions. They can't steal your coins though - your private key is never shared with them.
BTW if your netbook has wifi then make sure you turn that off in the BIOS.