What is the drive filling up with? Have you had a look at the current processes that are running (by pressing CTRL - ALT and Delete)? It may be worth Googling each process to see exactly what they do and whether or not you need them. You can then start eliminating the ones that are not required or are suspicious.
Also worth checking you start-up items prior to doing this.
You can download a free start-up manager if you click here