Mixing WAN and LANs

[baffles]

Hi there. I cant work out how to connect an established working LAN to a new wireless router/modem. I connect to the new wireless router/modem just with my laptop fine but I would like to hook up my little LAN to the Internet as well and the modem/router had to go in another room. I'm a scrooge and don't want to spend much if any money well OK ill spend 50 bucks and no long cables as Mum will kill me.:eek:
The LAN goes through a Dlink DGL-4100. Is there a simple way of connecting my LAN through my laptop to get the Internet connection?
Also when I connect my laptop to the DGL-4100 LAN I loose Internet connection. How can I get both connections to run at the same time?
Oh the laptop is Vista prem if that makes any difference.

Cheers!

[MadKing]

http://www.smallnetbuilder.com/content/view/30740/229/

[StDubious]

Thanks for the reply!
We have a Thompson tg782g router modem supplied by our ISP and it has hardly any access to its configuration. I cant even see the settings for DHCP. I would still need a cable from my upstream to my downstream router aswell. What are my options now? Shoud I just replace my dlink router with a switch? I really dont like that thomspon, might look at replacing it.
Thanks again.