Make sure the router isn't located close to a mobile or cordless phone or any large metal objects, in particular, central heating radiators - any of these can cause problems.
If any of the computers are to be used in the same room as the router, connect them by ethernet cable rather than wirelessly. A wired connection will always be faster and more reliable.
Try changing the wireless channel number from its default setting, which is normally 11. Initially, disable any encryption (WEP or WPA) until the network is working properly.
<<< the minute i move them out of the room signal lost. >>>
What are the walls made of? I did read about one new house that had been built with aluminium foil lining the walls for thermal insulation and that killed the wireless signal totally from outside the room.