Which part of the hard drive do I delete to get rid of old OS so I can clean install my upgrade.

I have 4 partitions to my hard drive, it states to delete the one with the old OS in it but I am unsure exactly which one that is.

I have partition 1 (system) thinking its this one?

Partition 2

Partition 3: Recovery ( this could be it too)

Partition 4: HP_tools (probably not this one right?)

Partition 1 will be your system partition. The recovery partition is there for if you ever need to recover your system back to factory settings. The HP tools are utilities which you probably don't have a lot of use for. If you are making a clean install of a new system I would:

Burn a set of recovery dvd's using the supplied HP utility to keep a set of disks from which you could make a recovery to factory settings if ever you needed to. This means you would no longer need the recovery partition. You could then also get rid of the tools partition - most people don't have a lot of use for them and they are likely to be of even less use under a new op sys.

You could then repartition your entire drive to have just a partition for your system and installed apps and a second one for all your data.