We're currently using fontconfig for enumerating and matching/selecting fonts on windows. FreeType is used for rendering. It's a bit of a pain, because fontconfig's cache needs to be initialized at least once for every user and installation. And that can take a long time.
Windows also seems to provide an interface for font enumeration. I found the following: http://msdn.microsoft.com/en-us/library/dd374109(VS.85).asp
However, there is a problem. To quote the documentation:
Note that charsets are a legacy notion corresponding to pre-Unicode character sets. At this time, there is no mechanism to enumerate fonts supporting arbitrary scripts or character ranges in Unicode.
The workarounds described seem to be quite complicated. Is there no modernized interface available (on newer Windows versions, maybe)?