Two options to suggest - try on just the one PC first and see what happens before you trash the other one too
Uninstall the Linksys software, reboot the PC without the wireless connected, then clean out any windoze wirless settings, and any remnants of USB drivers. Use safe nmode if need be. Reboot again.
Now strictly follow the Linksys manuals for installation, in the sequence they tell you whether this is plugin the USB first before running CD, or vice versa. Use only the Linksys programs to setup the network, not the M$ options.
Alternatively, once you've wiped the lot, explore the linksys CD and copy only hte USB drivers to your HD. When you now add the USB connection, if drivers are required, point the installer at the HD copies, don't use the linksys installer so you don't get all the other addons. Now use the windoze wireless setup.