It is generally known that disks are all initialized as basic for your Windows 2000/XP/Vista/server2003, and the way to convert basic disk to dynamic disk is never strange for you, because dynamic disk, introduced since Windows 2000, boasts many advantages such as:
Disk and volume management tasks are performed without having to restart the computer afterwards.
Create volumes that span multiple disks.
Extend a simple or spanned volume.
Dynamic disks support an unlimited number (up to 2000) of volumes.
Dynamic disks do not use a Master Boot Record (MBR). Disk layout information is stored on the last 1 MB of the disk.
Although you benefit a lot from it, you need to convert dynamic disk to basic disk for some reasons, say, the system partition runs out of space, or the dynamic volumes could not be deleted when you try to reinstall the Windows Vista. What is the solution you choose to convert dynamic disk to basic disk? Is that making you at risk for data loss?
If you have a little knowledge of computer, you may know you can convert dynamic disk to basic in the disk management, while the point is that you are required to firstly delete all partitions on the disk and then convert the dynamic disk to basic disk. Things sound ridiculous!
Data comes first for most people nowadays, you may never want to reinstall the system or suffer data loss during converting. So, here comes an alternative for you to safely convert dynamic disk to basic disk: why not backup your system state, all applications or data on dynamic disk firstly, and then convert it? Say, use third party dynamic disk copy software EASEUS Partition Master to copy dynamic disk to external hard disk or another disk for data protection or backup, after you convert it to basic disk, then you can copy it back. 
Then, follow the detailed way to convert dynamic disk to basic disk and do as you like.
