disk management help needed

i have a question about partition management. i have an 80 gb hard drive with two partitions, one has my os and all that important stuff and the other is just there not being used at all. in the computer management console under disk management it shows the unused partition as free space and is bordered in green. what i need to know is how to return everything to one partition like it was before the second partition was created. do i right click on the free space partition and select the delete partition option? will that return the free space to my active partition making it all one again or will i lose all of that space?