When first intending to see a drive split the best move is to allow extra space on the primary OS host partition in the event you later need more space for additional programs or simply seeing more files added there. GParted will easily shrink the storage partition and generally sees less problems over the typical softwares like PM since it is far less involved seeing a basic structure.
With only a small amount on the second partition and enough space remaining on the first for ease and generally a time saver over moving a shrunk down second partition I would simpl copy+paste everything over to a temp folder and delete the second, iincrease the primary where you want it, and then create a new storage partition. Moving partitions is like zero filling a drive with an old dos tool since you have to leave that going for hours as it creeps along!
In Vista the Disk Management tool allows you to shrink or expand any secondary partition but is not advised for expanding the primary. This is due to having the OS being loaded into memory from the same partition. For resizing the first system/boot primary you need a 3rd party tool there.
Cromewell is quite correct when referring to most using the basic disk since server editions are most likely to see dynamic volumes. There are a few methods however for coversion from one to the other. Some MS information regarding the Server 2003 edition goes as follows.
Boot and system partitions. You can convert a basic disk containing the system or boot partitions to a dynamic disk. After the disk is converted, these partitions become simple system or boot volumes (after restarting the computer). You cannot mark an existing dynamic volume as active. You can convert a basic disk containing the boot partition (which contains the operating system) to a dynamic disk. After the disk is converted, the boot partition becomes a simple boot volume (after restarting the computer).
Mirroring the boot and system volumes. If you convert the disk containing the boot and system partitions to a dynamic disk, you can mirror the boot and system volumes onto another dynamic disk. Then, if the disk containing the boot and system volumes fails, you can start the computer from the disk containing the mirrors of these volumes. For more information, see
Create and test a mirrored system or boot volume.
http://technet.microsoft.com/en-us/library/cc757696.aspx