The base is 10.5 ” in diameter. Expandability: four screws on the bottom–will hold up to a gig of memory and an Airport card. Antennas built into the display. Three models. 15″, 700 MHz, 128 MB, 40GB, CD-RW: $1299. Next: 256 MB and a combo drive, $1499. Last: 800 MHz, 60 GB, and a SuperDrive: $1799. Moore’s Law in action, folks. Superdrive model available January, midline Feb, $1299 in March. (Learning curve effects to support the low price models.)