As far as I know, the only "crime" the Congressmen could have committed would be to (a) take gifts and (b) to have a quid pro quo for votes. Even then, I think that's only a violation of rules. And, to be honest, I don't see how Ney committed any actual crimes, from this article.
I'm sure I haven't gotten the whole story at all, but to read the media, Abramoff is pleading guilty to consorting with Republicans.