For school, this is mostly a matter of what discipline will you be studying and what software/equipment are commonly used within that discipline.
Everyone will need to be able to write papers, send and receive emails, and browse the Internet. (IT Services distributes a CD with common software, such as anti-virus and email programs etc.) You should arrange for your computer to have word processing software, such as Microsoft Word, as this is not provided by the University for you (although you can use this software in labs and classrooms).
In many areas of study, you will also need to be able manipulate spreadsheets, graphics/images, and web pages. Programs for these tasks vary, though Excel is nearly universal for working with spreadsheets and is part of the Microsoft Office suite mentioned above.
Finally in a few disciplines, you may need a highly specific or demanding software, such as video editing. Many computers are coming with basic video editing packages, but if this is something you will be doing routinely, then you should consider specialized hardware and programs.
To further determine what software you will need for your area of study, speak to your program advisor, as they will have more specific information of what will be required for your studies.
Since computers are often used for recreational pursuits, you should take your hobbies into account as well. For example if you are into music or photography, you will want lots of storage space on your computer for keeping data.
