I have problems with my Dell wireless. I tried tried to install Linksys wireless. Now the linksys has been installed on my desktop. But i dont see any wireless networks on the systrayit is not connecting to any wireless networks.

First--does your Dell have wireless capability? Most new computers do.
Next, is there a wireless switch that you must turn on--on the computer case?
Next--there is a Fn-Special function key combo that will turn on your wireless card. Did you press that combo?
Now look in you network connections--is there a wireless connection there and is it enabled?
You can also check in the device manager to see if the wireless card (under network devices) is there and is functioning. You may have to install or update the drivers.
Once you have installed or enabled the wireless device, you will see a wireless icon in the system tray.