Consider getting a dualie of any tower. It makes a big difference, G4 or G5.
Or get a refurbished 1ghz 12" Powerbook with Superdrive ($1199 - when they have them in stock), an OWC 512 RAM chip, an Apple Bluetooth keyboard, and a Mitsubishi 21-inch CRT. And sell your iBook. And when you want to upgrade to a tower when you can afford it, you'll still have a satellite system.
Or get a refurbished 1ghz 12" Powerbook with Superdrive ($1199 - when they have them in stock), an OWC 512 RAM chip, an Apple Bluetooth keyboard, and a Mitsubishi 21-inch CRT. And sell your iBook. And when you want to upgrade to a tower when you can afford it, you'll still have a satellite system.