I just finished going through this exact same issue. You do not actually have to create your template in older version. We have 2008 & 2006. I did all my creation and development in 2008. It is set to save down to 2000. When I tried running 2006 it did not recognize the format eventhough it was saved down. All I had to do is all of my development in 2008. Once I was happy with my template I opened it up with 2006 and saved it using 2006.
However we have 2006 on every machine and IT has now put 2008 on every machine (i think) problem is some folks are not using 2008 yet. don't ask why. But by having a template that is not compatible with any version older than 2008, it will force thos users still on 2006 to finally switch.