Emailed Linksys about WCF11 WM2K3 support and they sent their cookie cutter reply, "no, don't know, yada yada...."
Did the following as instructed in another post for the WCF12 card and it worked.
Have been able to access my network and use pIE. No look ActiveSync'ing over the network, but I haven't spent too much time with it to this point.
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To summarize here:
1) download and install the SL-2511CF & SL-2511CD / WLAN_ForWinCENET400.zip / Windows CE.NET4.0 driver from the
http://www.senao.com/service%20&%20...%20download.htm site.
2) Perform the soft reset and insert the Linksys WCF12 card
3) You should get the “unrecognized card” message. Enter “wlannds.dll”.
4) The friendly and familiar green link light should appear and your network should be visible.
You can ignore the message "Cannot find 'WLANSTA' " after you soft reset. This is for the WLAN Status Icon utility that was installed in the programs area, it's not required. You can just remove it from the Startup (via windows explorer)