More reasons to use both Google Docs and OpenOffice: the OpenOffice.org2GoogleDocs extension. Allows you to upload from OO to Google Docs or download from Google Docs to OO. Requires that your JRE is set up correctly in OO and is Java 6.
Without realising it I’ve become a big user of Google Docs, mostly by importing from GMail attachments. On rare occasions I find the 500 KB maximum file size to be a problem – I’d suggest 1 MB is a more sensible maximum – but it does encourage people to keep embedded content out of their text documents.