The GeForce 9400M is capable of displaying up to 2560 x 1600, at least according to nVidia's specs. If you want to output to a HDTV make sure you set the resolution to 1920 x 1080. You will still only be able to see a portion of the blue print at a time though, but at least the HDTV will have 50% wider resolution 1920 vs. 1280.
As stated, the 9400M seems to have a max output of 2560 x 1600 so another option is to display the blue print on a 30" PC monitor which has 2560 x 1600 resolution which means you can see even more of the blue print at a single time. However, you are limited to a 30" LCD monitor since there is nothing larger with that resolution (at least on a consumer level). I would connect your laptop to a 30" PC monitor and test out the resolution before buying if possible.
You will not able to view your blue print in 1:1 aspect ratio (i.e. "life size") because you will probably need a monitor that can display at least 5,000 pixels across. That means a monitor with a resolution of at least 6400 x 3600 if you are shrinking it down by 20% to fit the entire floorplan on your screen. I'm sure there are commercial monitors with high resolution like that, but you're probably looking at something which costs at least $50k if not extremely more.