Might be a good idea not to make derogatory references to other posters' actions.
If you really want just the one drive using all the hard drive space, you need to repartition. During the Windows install process, you would need to delete BOTH partitions, then create a new single partition in all of the available space. Yes, this would wipe out all of your data.
If you have no recovery disks, you will not be able to install any of Compaq's bespoke drivers or the additional software they may have included with the computer. You should go to the support section of their website and see what is available for download - especially drivers. If you can get everything working this way and don't need all the "bonus" software, you can continue on your way.
I must confess that I would find 10GB a little excessive, too. Unless it were in the context, say, of an 800GB hard drive...