First of all I just want to share something I discovered, which may be of interest for someone with specific problem like mine. 

I Posted this message in Dec 2010:  Link

Here is my original home network configuration:

But turn out that I need more connections, so I added a 8 port switch:

But in my room where the IPTV is, I also needed internet connections for upstair usage.  So this IPTV cable would have used up the only network connection.  So I thought I maybe able to add another switch BEFORE the IPTV to allow network cable sharing.  From that switch, one outlet will link to IPTV decoder, another outlet will be able to connect to another computer with wire:


But it failed.  Either the IPTV will not be able to connect to receive IPTV info, or the internet failed to connect when both are up.\
So I loss hope when no one can provide practical solution ...

Until last week !  When I read that someone can use an old wireless router to be used as Wireless Access Point !  HERE & HERE.

So since I have an old Streamyx D-link 2640b lying idle around.  I have decided to replace the 2nd switch (for the IPTV) with this old router as Wireless Remote Access Point upstair.  As illustrated below:


This surprisingly solve my months long problem !  As long as I follow the above link to configure the 2nd Router (as wireless Access point).  So with this configuration, I manage to watch IPTV while at the same time allow internet access either by linking to the router or through wireless access.
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The 2nd Router (as wireless remote access point) was originally TM property, so the firmware was specifically designed for TM.  I updated the firmware with the latest firmware from the D-link website (South-East Asia edition) before using it as Wireless Access Point. 

So those of you who already have home network cable in-place, one single network cable can finally used to connect IPTV & internet at the same time.