If you got a copy of the latest Microsoft Office, then you might have noticed it came with some new fonts that look better than the last batch of fonts Microsoft had designed for them. (Which seem no longer to be given away for free.)
These new fonts are called the Microsoft ClearType Font Collection. If you don’t want to upgrade your copy of Office, you can buy them from Ascender. But they’re not cheap.
But if you’re cheap, and you have any old copy of Microsoft Office, what you can do is to download the OpenXML file converter from Microsoft, and get them for free.
Update: I’m guessing that if your Mac came with a “trial” version of Office, that would be enough to install the OpenXML converter.