zoom makes a usb modem that is about the size of a pack of gum. i have used one with my macbook pro.
here's the description from amazon--zoom 3095 usb modem http://www.amazon.com/Zoom-3095-Mini-External-Modem/dp/B001FCIOSW on ebay, one of these might be cost-competitive with buying the airport plus a power supply. ken -- You received this message because you are a member of G-Group, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to g3-5-list@googlegroups.com For more options, visit this group at http://groups.google.com/group/g3-5-list
