Video and audio capture on Windows 7

I have some presentations coming up that I would like to capture the video and audio from my PC running Windows 7. I have not done something like this and was hoping someone could suggest a trust worthy and reputable product I can try, hopefully free but I am willing to pay for something for a decent price. Has anyone ever heard of a product that would allow you to bookmark the video kind of like a table of contents so you can easily jump to specific topics?

Also, the sessions will be from 4-6 hours each. Do you have an idea about how large these video files would be? I may buy an additional hard drive if needed, I probably have about 1 TB to play with now.

The main thing I need is capture a screen or browser, PC audio, and the ability to bookmark points in the video for reference later.