How to convert subtitled MKV to AVI?

Hi there, I'm trying to convert my Amagami SS episodes without luck, I was using a program called "MediaCoder" or something, but it would still give me a subtitled AVI file, even disabling the option.
I tried the MKVGUIextract (sp?) something .. muxing my MKV episode and erasing the subtitles, but then the MediaCoder program wouldn't recognize the new file :heh:

I really want to start with my AMV idea, but glorious Sony Vegas Pro doesn't support MKV files.

Uh .. I'm using UTW subs!