I was running in Ad-Hoc mode forever with a WaveLAN card on a Windows laptop, a WaveLAN card in an OpenBSD desktop (via an ISA PCMCIA adapter), and an iBook with Apple's 802.11b card. Until I upgraded to MacOSX, which no longer allowed Ad-Hoc mode (thanks, Apple!). Now I use the iBook as an access point using software that came with the OS. Interestingly, the other computers can communicate even when the iBook is powered off. I think that the AP might just kickstart the network, after which it can run independently. (On a marginally related note, MacOS9.2 does not allow the iBook to become an AP in the same manner as MacOSX, which means if I have to reboot to 9.2, I have to reconfigure my network. Until I discovered that sometimes the network name is still floating around out there, and I can join the network. Weird.)