IMO, Pyg is pretty much on target. XP uses the Windows "Wireless Zero Configuration" tool. It has a tendency to search for the strongest signal rather than what you've designated as a preferred network. There are a couple of things you can do:

1. If you want to keep using WZC, then you should know that everytime your laptop sees a new wireless network it adds it to a list of possible networks to connect to...and sets each one to connect automatically. You may have seen this list as the "preferred" list. You've probably put your network at the top. Well...if one of the other networks ends up with a stronger signal, your laptop will jump to it automatically. There is a way to stop this behaviour. Go into the "Wireless Connection Properties" screen and select the "Wireless Networks" tab. You'll see the list of WLANs...notice the parenthesis next to each one. I'm betting that all of yours read "Automatic". That's what allows the laptop to jump to the one with the strongest signal. Highlight the networks that you don't want to jump onto and click the "Properties" button. A window will pop open with "X Properties" (the properties for that WLAN). The third tab is "Connection". Click that tab...and DEselect the checkbox marked "Connect when this network is in range". Voila...your laptop will no longer try to jump to that network when it reads a stronger signal there. I'd suggest that you do this to the networks that seem to cause you the most trouble...neighbors, etc.

2. Turn off the WZC system and configure your wireless settings manually. The only drag with this is that when you go on the road, it can be something of an effort to find available networks...that's what WZC is really good at.

Personally, I'd go with #1 first. If that doesn't solve your problem, then go with #2.