How would you rate a computer with this configuration? What all multiple processes can execute in it?

I would say it can do just about anything you'd want it to, it might not run games on maximum settings, but it should run anything out there right now. With 4 gigs memory you can run as many applications and browsers as you want within reason and it will not slow down. It might slow if youve got a few 3D apps running, like video editing and games running at the same time, but nobody does that anyway.