My new MN-500 is slooooow

Just bought a MN-500 and it's slow. With my laptop sitting just feet from
the base station I can't get better than 500kbps throughput. Everything
else on my wired network runs fast including a PC that is plugged directly
into the MN-500. I've tried disabling WEP, firewalls, virus software, etc
but the speed is just horrible. I've also tried changing channels and
moving the base station as well. Everything in the house that emits a radio
signals has been unplugged but it doesn't seem to matter.

The NIC that I'm using is an Xterasys Cardbus PC card on Windows 2000.
There are a lot of errors, both Tx and Rx. Almost 1/3 of the Rx packets are
retries.

When pinging devices on the network(including the base station itself), I
get occassional timeouts/packet loss.

Any ideas? I'd be happy if I could just get 1.5Mps which is the speed of my
DSL line.