Two things here - first your laptop should have come with an HP utility program to burn a set of recovery disks as Mike as said - it is essential you burn these to enable you to run a full system recovery if and when you suffer a major system or hard drive crash. The exact method for doing it is system dependent so you need to read your user manual.
Secondly I'd strongly advise maintaining a regular image of your system drive using something like Acronis True Image (google for a free trial download). This is most easily done if you partitin your hard drive and keep just your op sys on drive C (40gb should be big enough but subject to your hard drive size you could make bigger). Use the remaining space to create a scond partition for...