Since the size of the digital art is always expressed in terms of pixels per image and Dots Per Inch (DPI), the tool will always draw on the same number of pixels. So, if the brush is 10 pixels wide, that same brush stroke looks way larger when zoomed in versus way smaller when zoomed out.
Heather - I just have this ordered myself and although I've never used it I have drawing friends who swear by it. When Amazon had it at 50% I had to jump at it. It was supposed to be here yesterday so hopefully today but I can post my opinion after I've tried it. I can ay all my art friends love it and we all work professionally. I do illustrations and comic books myself. Bt if I were in your shoes I'd spend the 40.00 for it because I've worked with lot of art programs and for 40.00 for something as powerful as this is supposed o be you just can't go wrong. So I'd take the leap.
The first tablet was probably a Wacom of some kind, my guess is one of the Intuos professional models. The large tablet monitor you saw was a Wacom Cintiq. Be aware that Cintiqs cost thousands of dollars, and are usually only worth it if you are actively making a living in a field such as concept art, matte painting, etc. You can do everything with a regular tablet that you can with a Cintiq minus draw on the actual screen, so it's really more of a convenience than a necessity.
Still, in college I had access to a lab full of Cintiqs 24/7 for four years, and they truly are awesome to use. Maybe if I ever have large amounts of disposable income...