You can't open acrobat then do a file/"combine" process? Acrobat will "combine" just about any file type. Make sure you're trying the combine function, not create. Could it be that acrobat 8 is too old and won't recognize a docx file? Try saving the document as an older type .doc file and combining it in acrobat maybe? I'm reaching here; haven't played with my office10 much as of yet and am not looking forward to it one bit.

No dice. Just tried it. My .docx files are not even appearing in the menu selection for combine files. In Adobe Acrobat, the file type selection menu does not have an "all file types." It only has an "all supported file types." It's hiding all Office 2010 files that I have created since switching to Windows 7 (64-bit) and Office 2010 simultaneously.