Desktop ping is fine while laptop struggles

Hi,

We have a desktop Dell 8200 and a Asus laptop W2. Both run windows XP SP2 and are connected to a wireless network (using a netgear DG834G). Reception is on the whole good or excellent for both machines.

My brother and I would like to play games together online or via our network. The dell has no problems with ping while wireless. However, the laptop has a undulating wave like ping profile (i.e. ping is fine around 30-50 and then it shoots up into the hundreds) I have noticed this isn't limited to gaming but also when surfing the net. When I ping websites through the command window the pings can be very low or extremely high. I have tried disabling norton anti-virus but this doesn't seem to make a difference. I don't think there is any adware as I have scanned with adaware and spybot S&D and also the laptop is only about 2 weeks old.

Also when we connect the laptop to the network via ethernet(100) the pings are fine. I am usually very good with sorting out computers but this really has me stumped. My only theory is that maybe the traffic in the air is clashing but that wouldnt explain why the desktop is fine.

Any help is much appreciated. If you need more info just ask. Take care,

Ollie