I have 2 pcs with win xp and a wifi router ( without outgoing internet connection )...my job was to connect them over wifi to share some files. router was properly configured, both computers connected to wifi without problems, but when I tried to network them I could not see them in workgroup...i changed their names and added them to same workgroup but i couldn't connect pc1 to pc2 ( i could ping router from each pc but pinging other computer resulted in ping timeout) ..now i cant figure out why this is not working since I've done this before on more complex networks and it should work but...( maybe I have gremlins hiding somewhere..)

edit1: Firewall is down on both machines( I disengaged it in both control panel and in services) and folder sharing and permissions are ok.. edit2: I know about Ad Hoc network ( wlan-to-wlan, without router/switch ) but that's not what I am trying to accomplish here :)