Does Electrum require the Satoshi client? Bitcoin Armory is a client that sits on top of the official bitcoin client. Bitcoinj is a totally different client, separate from the official bitcoin client. Does Electrum also need the official bitcoin client, or is it separate?
No, Electrum doesn't require Bitcoin-Qt to be installed on your computer. Electrum and BitcoinJ aren't full clients, though, so they do rely on Bitcoin-Qt at some level -- Electrum through the Stratum network and BitcoinJ through the Bitcoin network's SPV mode.