Reclaiming a hard drive partition

I am not a big PC hardware guy and a friend came to me with a question. If his hard drive has 2 partitions, can he reclaim the smaller one (that of course doesn't have his OS), into one drive using FDISK or any other utility, all without corrupting or disturbing the larger partition? In other words, will he have to start over and re-install his OS? Probably a very, very simple question, I am just not that knowledgeable in this field.

Partition Magic can do what he wants. Its not free though. I don't know of any software to do that, that is free.

Aero got there first as I read the thread, but Partition magic will be able to do what he wants, and the data won't be lost.