Various Networking Problems

[Sniper101]

Ok here's the low down i have 2 PC's and iv got them both set up right. My Computer is the Main one that the Internet Connection is on and the other PC goes through this.

Iv got my Network set up like this:

Family PC and PS2 Connected to Router

Router Connected to Ethernet port on my Computer

Then USB ADSL Modem from My Computer to Phone line

All this is Done via ICS (Internet Connection Sharing) on my computer.

My Problem is i can't connect from my Computer to the other PC Via Remote Desktop nor Remote Assistance or anything like that, the other Computer is able to do Remote Desktop to my computer but nothing else :(. And id like to be able to control the other computer without leaving my Room, this is due to i can't walk very good, and getting up my stairs is a pain.

Can anyone help me?

If iv gone wrong somewhere please help me really badly. If i need to Purchase any hardware please give me details of what i need.