Tested with fontforge-cygwin_2012_08_02.zip on Windows 7.

1. Download FontForge for Windows from unofficial fontforge-cygwin.
2. Extract the zip.
3. If the computer is part of an AD Domain, edit fontforge.bat. Replace the lines:

    if not exist "cygwin\etc\passwd" ( mkpasswd > "cygwin\etc\passwd" )
    if not exist "cygwin\etc\group"  ( mkgroup  > "cygwin\etc\group"  )

   With:

    if not exist "cygwin\etc\passwd" ( mkpasswd -l > "cygwin\etc\passwd" )
    if not exist "cygwin\etc\group"  ( mkgroup -l > "cygwin\etc\group"  )

   This is to prevent the passwd and group files from being filled with all Active Directory accounts and groups.

4. Open a command prompt and use it to start fontforge.bat.
5. An Open Font window appears. Click Cancel.
6. Copy and paste the following and save as otf2ttf.txt next to fontforge.bat:

   #!/usr/local/bin/fontforge
   Print("Opening "+$1);
   Open($1);
   Print("Saving "+$1:r+".ttf");
   Generate($1:r+".ttf");
   Quit(0);

   Source: Jérôme Jaglale - Intall OTF font on Ubuntu

7. Execute the following command in the command prompt and substitute the last parameter with the filename of the OTF font:

   fontforge.exe -script otf2ttf.txt font.otf

8. There should now be a TTF version of the font next to the OTF file.