Poor signal strength. i have a wireless network at home but with my new acer lap top when i log on

Question

i have a wireless network at home but with my new acer lap top when i log on the signal strength drops to 2 bars (very poor signal). however if i log of and look at the signal it is full bars until i log on then it drops again. any freinds who have brought there pc to my house this doesn't happen. they get the full strength signal. what can be done to fix this? i have checked with the router people and they say it is a pc problem.