Primary How To Merge A Logical And Primary Partition?

How to merge a logical and primary partition? - primary

I have a hard drive of 200 GB, divided into primary and 50 GB 150 GB logical. I am running Windows Vista that is installed on the 50 GB logical partition. I would like is to join the two partitions together as one primary partition is empty, as the two could merge partitions without losing anything, including the operating system outside of logic?