Collada is badly supported in Blender even in the version 2.49b. Which limitations bother you in the MD2 format? Maybe give a look at MD3. I already have a small MD3 importer that could be ported to use LWJGL.
Have you planned to use a 3D engine relying on LWJGL for the rendering (JMonkeyEngine, Ardor3D, JPCT, ...) rather than directly using this API?
To be honest I was influenced by the stuff I've read on random forums posts (not in jgo) about md2. Basically everybody says it's old and anything else should be used instead.
If animation export is not supported by Collada with Blender, that's a big drawback, since Blender is the only 3d tool I can (barely) model ...
Do you know how well Blender supports md2 export ? I know it does exist some scripts, but I can't try it right now since I'm stuck with my company's computer for a few weeks and can't install it here

I am not planning to use a 3D engine, not for the moment . I am intersted in learning the inners of OpenGL first and then if I see the need I might migrate to some engine .