It’s up to you, but I’d suggest waiting for the next refresh on the MSN Messenger 7.0 beta. Remember, this is a beta release.
Lora and I have both been experiencing system crashes after installing 7.0. Lora was able to get her system more stable, I haven’t tried yet.
This is one beta where I wished I’d have waited. Although the beta is touted as having more ink support, it’s an incremental improvement and things like undo/redo ink don’t always work anyway. There are a bunch of new features, such as Nudging, that you might enjoy. However, for me, I wish there was a new whiteboarding app that was really ink aware. Oh, and it would be good if it was able to connect more often than not.