Problems connecting to my wireless internet (see details inside)

On black Friday we bought a netbook and a PS3. We already had a laptop and an XBOX 360 and our wireless network was working fine( the Xbox is wired). Ever since we got my netbook we can’t have both the laptop and the netbook connected at the same time because our internet drops. We can have both consoles and one computer but not both computers at the same time. We’ve already checked the firewall settings and we disabled homeGroup on both computers and we’re still having problems. We also checked the IP address and that is not the problem either.

Does anybody know what else we can do to fix the problem or have any of you had a similar problem before?