I wouldn't use a PCI 802.11b card. USB all the way. My main machine has an Orinoco USB Gold adapter. Orinoco stuff is dope. Just my $0.02.

When you have a USB adapter, you can move it around to get better reception. It's unlikely that the back of your PC has a good line of sight.
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-Rob Riccardelli
80GB 16MB MK2 090000736