My 360 has a mfg date of Dec 14, 2005. I do not have the intercooler. I have heard the first revisions of the intercolor caused problems but have been fixed in latest versions.
Personally, I'd wait until the 360 is out of warranty I'd mod it to be cooler. There's two things (well, three if you include expensive watercooling) that you can do. Get the talisman replacement fan and/or an extra fan by hacking into a 12v source. Also one could redirect the airflow over the heatsinks.
http://www.llamma.com/xbox360/mods/360-12V-fan-Mod.htmhttp://www.foundmy.com/oscom/product_info.php?cPath=38_49&products_id=178You could even get this kit which has a temp gauge too.
http://www.foundmy.com/oscom/product_info.php?products_id=191However, I don't think you have to worry. I am going to put the quieter fans in there just to have quieter fans. As for over-heating I think that was just a problem in a small percentage of the launch units. What sucks is Microsoft could have made it quieter and cooler. I think they could have had better heatsinks tool.
You will know if you are over heating if the video starts to get pixilated.
Keep the power supply away from it. The only time I had my 360 overheat was because the power spply was right next to it adding to the heat. I've had the red ring once because of lightning.