I make singing videos and I want the quality of them to be improved so I am purchasing a new webcam. What webcam do you think I should get that has a good picture clarity and a good microphone built in?

I’m getting a new iMac now (switching from PC) and I was wondering although 3GB is the maximum, is that enough? Cause i’m maxing everything out. But, I wanted to do video editing, picture editing, podcasting, music etc. I also am going to be putting games in it like, The Sims, and all the expansion packs. So i’m kind of unsure whether I should be putting on these games on it, and if it will slow down etc.
3GB of memory.
The Specs. are:

3GB MEMORY
750GB HARD DRIVE
2.33GHz INTEL CORE 2 DUO

What’s another way to express myself on the web?
i.e. podcasting, blogging, vlogging
(don’t give these as answers, seeing as i already know them)

I have recording eqiupment on my pc. is there anyway where i can be playing live online? i think it is called podcasting or something??
thanks
and free!!!