There are other non conductive pastes. Check out the Tuniq series. MX-3 I think is the newest. I don't believe they are conductive.
The TX2 says its not electrically conductive, the TX3 doesn't say that. Not sure if it is or isn't. Lots of people like the OCZ freeze as well. I've never used it however so I can't say one way or another. Freeze and TX2 or TX3 are usually suggested around here.
Edited to add link.