Powerbook Firewire models (Powerbooks made in 2000 w/ builtin Firewire ports) can support up to 1 Gigabyte in of RAM. With the 1GB RAM loaded you loose the sleep battery swapping option due to RAM SO-DIMM Electrical Limits but, hey, you've got 1GB so who cares about the battery :-). The original Apple documentation that comes with the Firewire Powerbooks say it can only take 2 256Mb RAM chips in the laptop's two available slots but that was before the 512Mb chip became widely available. With the 2 available slots and 2 512Mb chip you've got room to burn w/ your latest videos, music, or gaming.