Hello, I have the same setup but im using a gateway instead of a router.
What you have to do is get a program to manage your DNS
in order to share an internet connection.
All you have to do is delete any information in the "DNS" part of your TCP/IP managment protocall (right click on device on network connections, then go to properties, tcp/ip should be there) then once you have done that you need to install a proxy server program on computer 1 (internet pc) i used:
http://www.youngzsoft.net/ccproxy/
Once installed on host PC configure the laptop to connect to the proxy program on the host pc. You can do this by:
going to internet options on the control panel
go to connections then to LAN settings at the bottom
then click the box labeled "use a proxy server..."
then click advanced and input the ip of the host pc and then put in the ports for ccproxy, which are all 808 apart from "socks" which is 1080 and "ftp" which is 2121.
Hope this helps, if not i can do remote assistance some time,
Alex