Ok.. well reading reviews on this webcam, it is very good. You can use this for Windows Live Messenger and other programs, like Skype. Any program that asks for a webcam, you will be able to select the VX-6000 as your webcam.
Here's a note: If you have Vista, when you plug the webcam in, don't install the drivers from the CD. Let Vista search for them on the internet
. If on XP, use the CD.
If using it in Windows Live Messenger, your contact does not require a webcam to see YOU on webcam. What webcam they have doesn't affect you. They just need Windows Live Messenger to see you on cam of course, or what ever program (Skype, etc).
As for WLM using up CPU and memory, it can differ. It depends on your computer specs, how many programs you are running at the same time, etc. Millions of people use it, so you should be fine using it too.
You'll be fine with your webcam, it's a very good one. Be confident.