I just checked that it doesn't work in WinME. I've already dealt with WinME compatibility in my CAB reader recently. The most famous problem is that all W-functions will fail, you need to check for each such failure and redirect to A-functions. It's still a bit of a hassle, of course

Of course, the very first thing that won't work is the CreateFileW function, since only the CreateFileA function will work in WinME.