For Google Talk, I use DialCentral. Works great, SMS support, stable as all get out... but no video. In fact, I've used this as my secondary "phone" for the last solid year. It's that clear and useful - the developer(s) of this app are top notch and very active.

For video, there was only Gizmo and it was spotty. I think I had to sacrifice a couple of cats and say some phrase backwards for it to truly work. From what I remember, aMSN worked quite well with video/audio. But I too have very few friends with MSN accounts that regularly use it to check with.

I'll be honest. Video on the n810 was truly never utilized properly. That's been my biggest gripe.