Setting dual connection - monitor+tv

Hi,
I would like to keep my win7 system connected simultenously both to a tv set and a monitor. My tv is connected via hdmi to a Lg tv set and my monitor is a Samsung syncMaster 940bw.
My problem is htat when the pc is connected to the tv set, my complete win7 session, from the BIOS related Post phase to the win7 session isn't seen on my monitor.
In winxp, I had to choose between my monitor and my tv. I kept the pc physically connected to both tv and montor, and chose usinf my software. Now, with win7, this doesn'r seem to work.
How exactly do I set the needed configoration?

I have my 37" Vizio connected through the RGB connection it has which is labeled in the manual as the PC connection. It utilizes the full HD so there is no loss of ability, rather than the HDMI connection which does exactly what you are stating I use the DVI to 15 pin converter to connect to the RGB input and end up with a signal on the monitor and the TV. If you have an RGB connection on your LG it will probably do the same but be sure to choose native resolution when you choose it as the monitor in W7.

I am also experiencing this problem. I have a dell monitor (DVI) and Mits 65" which is hooked up via HDMI. The bios and boot screen appear on the mits whether it is on or off, but them the computer actually swithes to the dell after this!

Anyone know what the problem is?