Use Office 365 business with Dropbox Pro

You can try cloudHQ for Dropbox: http://cloudHQ.net/dropbox This service synchronizes Dropbox with Google Docs. Also there is a Google Chrome extension which enables you to manage (copy, move, etc.) and even edit Dropbox files directly from a Google Docs interface: https://chrome.google.com/webstore/detail/iobcbdgacfkninlcbphihhdlkobkehia

Whilst it is possible to unlink other computers through the web interface, as slhck noted, this leaves all of your files where you don't want them. Depending on the sensitivity of your files (and how much work you want for yourself) you can:

1. Back up all Dropbox files locally
2. Delete any sensitive files from your Dropbox
3. Wait for the sync to remove these files from the remote computer
4. Unlink the offending computer(s) from https://www.dropbox.com/account#security
5. Return the backed-up files to your Dropbox for re-syncing

It might be worth leaving any other synced computers off (or disabling their syncs) during this process to avoid the sync deleting/restoring where unnecessary.