Having Trouble getting network setup in windows XP

My wireless LAN consists of Dell 2350 router, 2 Del 1450 USB 2.0 wireless
adaptors connected to a Dimension 3000 and Dimension XPS T450, and a True
Mobile card in my Insperon 4100 laptop. All are running Windows XP. The
Problem: Most of the time the WLAN is not 100% up and running. That is, the
only way to communicate with another PC on the WLAN is to type its IP address
in the Run section of the start menu. Then rather slowly the local network
screen appears showing the shared files on the other PC. At this point when I
open the “My Network Places� screen and click on “View Workgroup Computers� I
am unable to see the network computers. If I reboot the router the network
works normally for about an hour-I am able to see the other computers on the
network and I see the shared files when I open “my Network Places�. After
installing a Dell 2350 replacement router, as suggested by Dell online
support, I got the same results. Wireless internet works fine on all units.
If anyone has experience with this issue your advice would be most welcome.
RWW.
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RWW