I need help about connecting to wifi

[nartin]

here's the problem:
all the laptops in my home and my psp can connect to the home wifi anytime/all the time, but my lap top can only connect about 50% of the time. sometimes while using internet, my laptop looses wifi connection, and if i try to reconnect, i'm lucky enough to get it work again.
usually when i don't need to go online, it works; and when i need it, it doesn't work
i think something is wrong with my laptop setting, not the wifi system; but i just couldn't find the solution

router: wireless-G, 2.4Ghz, 802.11g

any ideas?
thanks