I recommend Remote Desktop for Mobiles
which currently runs $35.00. I use it to monitor both my computer at home and my laptop at work. It works amazingly well considering you are viewing a live computer preview via a Blackberry device. You obviously need an unlimited data plan if you plan on using this type of software as it sends/receives constantly to update the screen. Once you are connected to the machine, you can view the entire screen, zoom in on a portion of the screen (choices are 3x, 2x and 1x), send keyboard commands, mouse commands, type on the screen, etc.
I have attached some screen shots of what it looks like on my Blackberry when posting this response. The first screen is full desktop view, second screen is 3x zoom, third screen is 2x zoom and fourth screen is 1x zoom.
If you need any additional information, feel free to ask.