Internet sharing pre paid wireless

A friend of mine has just bought a prepaid wireless internet package which comes with usb stick with 3G Modem sim card inside.(No phone line needed) It works fine but he's got another computer and i'm trying to set it up with internet connection sharing.Both computers are connected to a Belkin Router with network cables and both have file and printer sharing and internet connection sharing turned on.

Going to My network places on either pc you can see and access the other pc's hard drive fine.However getting the internet working on the pc with out the usb stick plugged in is another matter.1 pc with usb stick plugged in browses the web fine.

All firewalls from both pc's and Router are turned off.Under System Properties,Computer name under Workgroup,both pc's are labeled Workgroup.

On the pc with usb stick,when going to Network connections i see the wired Lan connection (Connected to Router) and the usb stick 3G modem listed.The problem is when i right click on wired Lan,Properties,Advanced,the internet connection sharing is NOT shown.Although on the other pc it's listed under right click on wired Lan,Properties,Advanced.

Anyway on the other pc which shows Internet connection sharing,i've enabled it.Then tried plugging usb stick in this pc to browse the web and allow internet connection sharing from other pc connected to Belkin Router but no go on other PC for internet.

If i turn on internet connection sharing on wired Lan (connected to Router) i see picture of hand.BUT aren't i meant to enable internet connection sharing on the usb stick modem listed?If i do this the hand leaves the wired Lan and goes to the usb stick 3G modem.Which am i meant to share for both pc's sharing internet?Share wired Lan or share usb stick 3G modem?

Belkin Wireless G (Although connected both pc's to Router with cables) F5D7230-4 V6

Router reset to factory defaults.