Hi - My understanding is that 99% of 2003 version macros should work in 2007 or 2010. However 1% doubt is for the 9 object models that have been removed in 2010 (I recall some changes were made in reference libraries as you also pointed out). Incase you are using some of these models that have been removed I believe you have no option but to replace them with the new ones. See the link below that highlights "Potentially Impactful changes in 2010"

http://blogs.technet.com/b/office_re...ect-model.aspx

Hope this helps...