the only difference u can see visually in the first look is the "royal theme" that gets installed in windows mce 2005. otehr than that when u look foir the version etc everything.. its the same. personally i cudnt find anything either. go to run-> cmd and then type "winver"
if it shows the version as 5.1 build 2600 xpsp_2_gdr-050301-1519:service pack 2, then its mce 2005. this is wat i got from different forums.
/legolas