I'm running 10.6.8 and I just downloaded ADE 2.0 from here:
I had accidentally installed 3.0 but I just ditched it by deleting it and that seems to have worked.
Initially the 2.0 version didn't show up so I just shutdown and restarted and re-ran the install ADE 2.0 dmg and installer and it's working fine so far.
I have Snow Leopard also, and version 2.0 is the one to use. Works fine.
Thank you guys! Had that figured out after a while myself. Main problem was: somehow overlooked the link to the previous version.