and in term of software. there are other ways to get office without using 2 operating systems. *cough cough limewire*.
and boot camp basically let you install windows on mac and then you can choose to start up your comp in either windows or mac os during start up. Parallel means you are running both at the same time. i.e. you go into mac os and then have windows running in the background. personally i would go with boot camp is nothing else, boot camp is free and you have to buy the parallel program