Yes. If your computer's video card is HDTV-compatible, it will probably have two or more video outputs. Connect one to your computer monitor and another to your HDTV. Both of them should automatically display what's on your computer.
After connecting my computer to an HDTV, why can't I see certain windows on my computer monitor anymore?
This is normal. Certain kinds of computer information, such as games and video, will only appear on the HDTV. You will see a blank screen or a blank window on the computer monitor. To see this information on the computer monitor, you must temporarily disconnect the HDTV.
For more help, please refer to the manufacturer supplied documentation or the Windows Help and Support where this information resides.