We have an old laptop here with WinXPSP3, and several other laptops, some of which are XPSP3 as well. All of them are able to connect to our non-SSID-broadcasting router, except this one. We've added the SSID the exact same way as on the others, but no matter how many times I delete and re-add it, or reboot, it doesn't seem to ever show up on the list when I refresh it. I set the option in the specific network itself saying connection whether it's broadcast or not.
Also, it connects to other (random) networks it can see, just fine.