Just an update on this.  Went back to a 1.6 stable kernel (which 
hopefully doesn't have smp) and am still seeing a problem.  The thing 
that is striking is the collision rate:

  packets  errs  packets  errs colls   packets  errs  packets  errs colls
    69400     0    89324     0 34058     74083     0    94634     0 34058
        0     0        0     0     0         0     0        0     0     0
        9     0       10     0     0        12     0       13     0     0
        0     0        2     0     0         0     0        2     0     0
        8     0        9     0     0         9     0       10     0     0
        0     0        0     0    62         0     0        0     0    62
        0     0        0     0     0         0     0        0     0     0

Especially given that the only things on this wave lan are a mac and an 
airport.

wi0: flags=8863<UP,BROADCAST,NOTRAILERS,RUNNING,SIMPLEX,MULTICAST> mtu 1500
         nwid yyz nwkey *****
         powersave off
         address: 00:30:65:01:37:c9
         media: IEEE802.11 autoselect
         status: active
         inet 10.0.1.11 netmask 0xffffff00 broadcast 10.0.1.255

wi0 at obio0 offset 0x30000 irq 57: 802.11 address 00:30:65:01:37:c9
wi0: using Lucent Embedded WaveLAN/IEEE
wi0: Lucent Firmware: Station (8.70.1)

Andrew