I don't know if I'm the only one who thought about this particular angle or not, but really I think you may have asked the wrong question.
Really what you need to be asking is "Should" you log in from your office....
Remember that while you are using a network system other than your own personal one, there is no expectation of privacy, and anything you do or say could be held against you not only in terms of your continued employment, but also in a court of law should the corporate policy be to report any nae-do-wells, (which is the case with most major corporations)
If they have a halfway decent IT department you are going to get caught eventually.
$.02