Handy tip - under Windows if you press alt-printscreen it captures only the active window.

for recording the screen you can use Camtasia Studio Latest version...
for XP user: use Camtasia Studio 6

And a to take Snapshot of your Screen then hit the "prtsc" button on keyboard... (print screen) and open Paint and then paste here...

and save it as PNG for best quality

For Video (avi) is best (I think so)
for image (png) is best (I think so)

I just use the "snipping tool" on my laptop. Hit the start button and in the "search" box, type in "snipping tool". Save it to your menu. It's easy to use and convenient, without having to download software.

Snipping tool: While just take out screen shot of your screen, If he really wants to do that then he may also use "Print Screen" button of his keyboard and then go to paint or any tool where he want to paste it using Ctrl + V

But here the Question of Recording Screen, and on this point:
I will like to say that Camtasia Studio 8.1 (uptill now-latest version) is the best, as Capturing HD Screen with Graphics and all so.
[I am not Promoting camtasia, I am saying fact, as I try many recorders. and find this one as usefull]

I’m currently using free online screen recorder. The recorded video is in great quality and can be shared to YouTube immediately with just one click. Also, it’s absolutely free without any restrictions like watermark or time limits. Hope this tool is helpful to you.

My Favorite Tool is Skitch from Evernote.

Nice list of tools! I recommend you to add My Screen Recorder Pro to the above list. It is a powerful product which provides screen capture, video editing, scheduling, uploading and screen draw features. This application is all-in-one package to create and share your videos.