I've found the Windows default soundfont, which has some really great sounds (like the lead from Porter Robinson's "Sad Machine") but it's in .dls format. Ableton's sampler can import .sf2 files, but not .dls ones. Does anyone have or know of any programs that can convert this so that I can use the sounds?
You should be able to use a SoundFont editor to open a .dls file and save to a .sf2 file. I was able to do this using Viena, a free Soundfont editor you can find here: http://www.synthfont.com/Downloads.html
This is a bit of an old post, so I don't know if you still need help, but I figured I'd answer anyway just in case someone else finds it useful.
While it could be considered expensive, Awave Studio has been around for decades and can convert between hundreds of different audio and music file formats - including .dls and .sf2