I also am using dcd's 2.10 ROM but didn't notice that Acrobat Reader was missing until I read your post. So I installed acrobat from
http://www.adobe.com/products/acrobat/acrrppcdload.html
and it worked just fine. Resco Explorer can change files associations as well as other free programs, or you can delete the default key within the registry at HKCR\.pdf to reassign it through windows