Opening DocX Files
Google Docs sometimes does a better job with .docx files than Open Office does-- but definitely no guarantees.
What should work -- though I wouldn't stake too much on this -- is to get a Windows Live account with Microsoft, upload the .docx file to your Microsoft "skydrive", and use the "Edit in Browser" option (which surprisingly sometimes works even on Linux). Since you're using Microsoft's own software, everything should be OK. I often get something to the effect that the document contains things that only work in standard Word, however, and then it won't let you open it. (Microsoft trying to get money out of you, of course.)