Now unless you are on a computing course at your university you may not be aware that most universities offer student editions of the software for free for their students, this can range from software such as Photoshop and Office, and operating systems like Windows XP/Vista, however if your university doesn't offer this here is a list of software that you can use if your computer doesn't come with full software pre-installed.

MS Office replacement: OpenOffice, which is a completely free and open source office suite available on all platforms (Windows/Linux/Mac) and has very good document format recognition so any documents your friends send you, you'll be able to open. It provides a replacement for Word, Excel, Access, Powerpoint and Diagram creation. Get OpenOffice at:  http://www.openoffice.org/

Anti-Virus replacement: Clam AV and AntiVirusGuard, virus protection for your home computer. It's most likely even if you got virus protection on your computer 'free' it will expire within a year in most cases and then your open to attacks. ClamAV is for unix systems and AVG is for Windows  systems. Get ClamAV at: http://www.clamav.net/ Get AVG at: http://free.grisoft.com/

CD/DVD Burning replacement: Burn4Free, a great cd/dvd burning application supported by adverts (which can be uninstalled after installing Burn4Free). This is a windows application which will allow you to burn data/iso's and music to cd's and dvd's. Get Burn4Free at: http://burn4free.com

These are the most common applications which you are least likely to get for free and in full with a new computer running Windows, for other free software which maybe specific to your course ask your tutor for information or check out:

http://en.wikipedia.org/wiki/List_of_open_source_software_packages

For lists of free software which you maybe able to install on your system.