my computer is an HP Pavilon 514C. It comes with one 80gb harddrive, but it is partitioned into 2 hard drive one c drive that is 75Gb which has my operating system, and the D drive that is 5GB for restore. This came with my computer when i bought it. It doesnt have any restore disc, but comes with a program that I can make. What i want to do is merge the two drive together safely without messing up my files or operating system. what programs or what do i do to do this effectly. thanks.

You can do this with Partition Magic. The contens of one partition will be moved into a folder within the other partition. But, I guess, the file systems must be the same on both drives

Once you've made (and checked - best make two copies) the rescue discs and you don't need the contents of the rescue partition any more, you can just delete that partition with a partitionning tool such as suggested by Oleh. This tool will then also allow you to increase the size of your C partition to the full hard disk size. Unfortunately, most of these partitionning programs aren't free.

Personnally, I would keep a D partition for data storage. You can make the C and D partitions both 40GB or 30/50GB for example.