To answer your question:
In the case of Outlook 07, we are actually trying to emulate the Word engine inside the browser you are running your test in. Most of our testing (to date) has been done using Firefox, so you will usually get the best results using that browser.
However, please take note: Our service is still in Beta and Outlook 07 is one of our top priorities. If you come across a discrepancy like this, please be sure to use the “report a discrepancy” feature within the test result. When you submit an open ticket we store the test in question and we can rectify the issues quickly and efficiently.
We really appreciate the feedback, it’s users like you who will help us refine our test results to ensure 100% accuracy!
Thanks 
