802.1X connection drops at client end

Hi-

I'm trying to work out what's wrong with my home wireless networking.

I bought a Belkin wireless G router (model F5D7230-4) and a Belkin
wireless G pci card (current version 5.87.19.106) for my pc. Using
802.1g setting with encryption, my pc would drop the connection
regularly, even when uninstalling Belkin's own client network software
and using xp's own wireless networking software.

I have an old 802.1b tablet pc, so have temporarily dropped the router
down to 802.1b and used no encryption (just using mac address
filtering). I'm not keeping settings like this - I just want to work
out what's breaking.

Anyway, using 802.1b with no encryption, my tablet pc maintains a
connection using "ping -t www.bbc.co.uk". However, my desktop running
a similar "ping -t www.bbc.co.uk" shows drops as follows:

Reply from 216.105.167.65: bytes=32 time=98ms TTL=51
Reply from 216.105.167.65: bytes=32 time=81ms TTL=51
Request timed out.
Request timed out.
Request timed out.
Hardware error.
Hardware error.
Hardware error.
Hardware error.
Destination host unreachable.
.... ~20 more of these...
Destination host unreachable.
Destination host unreachable.
Reply from 216.105.167.65: bytes=32 time=84ms TTL=51
Reply from 216.105.167.65: bytes=32 time=95ms TTL=51

So. it seems to be my desktop pci network card that has the
problems...

the router is runnning Belkin v9.01.05 and says there are no updates
when I check the software. Previously, I used the Belkin client
software for my pc, and it also said that there were no updates for my
pci g card.

Can anyone think of any reason why my pc networking flakes so easily?
Could it be because of old motherboard firmware? I'm running on an old
Asus A8V deluxe board - might I need updated firmward drivers for the
motherboard/ PCI bus?

Getting really frustrated here - hope anyone can help.

Thanks...