The preferred method of Converting a dynamic disk to a basic disk
requires to delete all partitions.
This is not something you want unless you are willing to spend several hours to backup, reinstall Windows and restore
your data. In addition you need to have Windows 7 installation DVD and a third party partitioning app like GParted Live.
But, there are some other approaches. One which is free is TestDisk
. How you can do it is graphically explained here
: The tutorial is good and there are several success reports. However It's very experimental. Use it as your own risk.
Another one which is commercial (US$ 29.99), and which a user has reported success
in using is Dynamic Disk Converter Professional Edition