XP, and a wifi-network-killing laptop.

Brought a Dell laptop home, running XP. Whenever I try to get it to connect to my home wifi, it does not do so, and in the process takes down the network, somehow. My router is in the basement, my iMac and iPod Touch run fine whenever this thing is not around. But once I try to connect with this laptop, the wireless disappers, and so does the internet on the computer that is wired to the router.

It seems the Dell does something to the router to make it not share its internet but why?

I know this is Mac-Forums but ya'll are smart and I thought I'd try here first.

Some questions for you...
How are you connecting with the Dell? (usb adapter, etc..)
Has it been on the internet before? (any network?)
Which router are you using?
What is the internet connection? (cable, DSL, etc..)

Before you turn the Dell on again, can you get a quick list of your various IP addresses together? And then, get the IP for the Dell? ipconfig /all from the command line will get you the same info as ifconfig in OS-X.

My gut reaction is that the Dell has had an IP address hard-coded into the interface that is the same as your wireless router. This would cause immediate IP routing conflicts that would affect every machine on your LAN. It may not cause the wifi signal to disappear, but it may cause the processor to lag and just not display the data, as it's trying to reconcile the IP conflict.

Does the same thing happen if the Dell's wifi is turned off and it's connected via Ethernet cable?

Seems to have been the router. My father took the Dell to a local wifi network and it was fine connecting. Got a new router to replace our WRT54g. He got the WRT54GR...i think. Seems to be faster and connecting nicely. I think it was the IP issue. When the Dell was trying to connect, the hard wired PC displayed some kind of IP error, then it disappeared. Problem solved. Thanks all.