Which online training/conferencing solution is the best?

Hi all,
I am having a very small business and I frequently need to collaborate with people from all over the world. So an online conferencing/collaboratin... software is a must for my business.
The key features I am looking for are:
(1) A white board with Internet audio (no need for video).
The while board can be multi-paged, and can be saved for later review. The voice conversation can be recorded and saved for later review.
(2) Sometimes also need application sharing, but users cannot control my computer without my consent. Secure is need
(3) My IP address and identity won't be shown: since I am doing online collaboration -- I don't need to know my collaborators in real life and they don't need to know me either.
(4) Good connection, with 24x7 connection. The connect will be down.
Any recommendations for the most cost-effective solutions? I mean high performance, easy-to-use, with the best pricing?
In fact I just need a whiteboard, I can use Skype for audio. Any thoughts