I'm trying to set up a wireless network to be able to use my laptop, but am having problems getting everything working; The wireless is "Connected" yet I'm unable to access the internet, or ping the default gateway.

The current setup consists of a Zyxel Prestige 643 (The "internet gateway", a wired router ) on the floor above, with a cable leading down to a Zyxel Prestige 650HW (wireless router) in this room, to which is connected my Desktop and recently acquired 'nix box via cable, and in theory at least the laptop (Toshiba Satellite p100-240 / Intel 3945ABG wireless adapter) via the wireless. The eventual aim is to set them all up on a "subnetwork" (through lack of a better word)

The computers connected with the wired connection to the second router work fine, with the same ip addresses/settings as before; I can still access and configure the upstairs router, but the only way of accessing the wireless one downstairs is to unplug everything from it bar the connection to a PC, and reset all the settings under network connections. Only then does the computer find it, and it becomes accesable through telnet/ browser. Does the second router need setting differently as it's, in effect, a router within a router?

After a fair amount of fiddling, the laptop now registers and connects to the wireless network, yet as mentioned there's no internet access, and no ping response to any machine/router. The TCP/IP settings are exactly the same as on the desktop, bar the last 2 digits of the IP address.

Operating System is XP Home on the desktop, XP MCE on the laptop.

What you need to do is have THREE networks. 2 Wired and 1 Wireless. The first wired network is the router upstairs. The 2nd wired network is the network BEHIND your 2nd wireless router. The 3rd is the wireless of course.

So now for connecting them, and this is where your problems might be, you need to connect the WAN side of the wireless router to your LAN side of your wired router. It sounds like you connected the LAN side of your wireless router to the LAN side of your wired router which would explain why you can get your laptop to "connect" but not reach anything.

This is the first step in getting you to where you need to be (the physical step). You may still need to do more configuration but I'll wait for your answer before moving on to the next step to see if the above helps.

Casey