Semi-n00b network problem

I am having a problem with a network I've set up. The network consists of a domain controller running Server 2003 with DNS and DHCP enabled, a wireless router, an ADSL router and a handful of client PC's wirelessly connected through the wireless router. The domain controller and ADSL router are cabled to the wireless router. DHCP is disabled on the wireless router, but enabled on the ADSL router. The network uses a basic 192.168.0.0 IP address range, with the domain controller and wireless router having static addresses. The ADSL router has a different subnet and a static IP address of 192.168.1.254.

My problem is that firstly, the ADSL router is a shared router residing in a comms room of which I have absolutely no control. I cannot disable the DHCP running on it. Secondly, despite the ADSL router being the default gateway, and being listed in the DC's forward lookup zone, the client PCs are not receiving an Internet connection. However, the DC is, so I know it's working.

I suspected that this was possibly due to the DHCP clashing so I disabled it on the DC and set up all the clients manually with a static IP address and pointing them to the ADSL router. This works ok and gets them an Internet connection. However it is not ideal because if, say, a laptop was required to be wirelessly connected to the network, it would pick up a DHCP address from the ADSL router and get Internet connection no problem, but it would not be visible to the regular network.

I'm I right in thinking that this can be solved by changing the network's IP address range so that it is in the 192.168.1.0 range? I've been trying to sort it all day and now my brain is frazzled, so any suggestions appreciated, thanks.