To convert Dynamic to Basic without wiping the HD first, use free Partition Wizard bootable CD before version 4.2 after which it became a paid feature. pw422.zip ISO - Windows Live
Download and burn to CD using WIndows Image Burner, boot PW CD, rightclick to delete any partitions you added which tipped it to convert to Dynamic. You can only have four Primary partitions or 3 Primary and unlimited Logicals. Once you no longer exceed those limits, click on HD to highlight it, from disk tab select Convert Dynamic to basic Disk, OK, Apply steps.
Watch this video to see how it's done exactly: How to convert dynamic disk to basic disk with Partition Wizard?
If you will then post back a screenshot of your Disk mgmt drive map and listings we can advise you how to add new partitions as desired.