For some reason when setting the 2820VN to use channel 13 (my preferred channel since no one ever goes up there) none of the Macs could connect, although they had been previously connecting perfectly fine to a Linksys WRT54G running tomato on that channel. Dropping the 2820VN down to channel 3 solved that problem and all 3 Macs have been running fine since.
Just for info, my other half has a Toshiba branded laptop with an 802.11g WIFI card running Windows XP that refuses to operate on Channel 13 regardless of access point manufacturer - even Cisco. Works fine on 1 through 12.
