If I can make a suggestion: Don't replace your existing, stable Skype. The new one throws away their previous UI and some of the changes are REALLY pissing me off. I usually have Adium, Colloquy, and Skype all lined up in a Spaces screen nice and neat with my current chats. Skype 5 makes this impossible, forcing you to have everything in one, excessively large window. You'll see...
Also, some features which I can't live without seem to have been excluded. (sharing only a portion of your screen, for example)
YMMV but I think the designers suffered a case of "Don't fix what ain't broke"
