An overdose

For as long as I have my pc (3years) I have used only 1 GB of my harddrive. Now I find I have used nearly 3 GB and cannot find the reasons for that. I have deleted all my programs in the hope that it would be corrected but gained only about 30 MB. I delete my internet files every time and there are no tempory files to delete, its all clean. Where does this massive 2 GB spring from? I did not download anything, it happened overnight and I have only a few spare MBleft.
Is there anyone who could help me there. I would be most grateful.

One thing you could try is picking up a free utility from www.download.com - Utilities - File and Disk Management.
Filter by your OS and freeware licence and you should find something that could analyse your disk and report file and directory sizes.
I performed a quick check and found utils like TreeSize, Diskdetective and Disk Analyzer - none more than a few hundred KB, so an easy download.

That at least would give you an idea where the space has gone.