I have finally finished upgrading, 'combining' and repairing the computers, my own as well as a number of others. I managed to get two computers working for our friends, the computers I didn't get to work, I pulled the hard drives out of them and installed them in the working computers.
For my own computer I ended up buying a whole new motherboard, graphics card and CPU chip as well as Windows 7 ultimate. A kind friend gave me 2GB of ram, all up it cost me $400. I was also given a big new power supply and computer case from our friends, whose computers I fixed. By building a new computer it ended up much cheaper then buying it already made from the shop. Originally I was only planning to buy a couple of parts.
I have been taking notes on what I did and learnt for my school work, I'm planning on posting about it at the end of the month.