Use Partition Magic software, this is a program you can use to make partitions without reinstalling everything, you can do what you wan. for me the best option is 10-30.
About the DVD drive letter, do not worry Partiton Magic performs a rutine to update the windows registry to replace all the references to the old drive letter and replaces with the newone.
Be careful though, because theres is a little possibility that running this software could ruin all the data in your hard drive. It's never happend to me, but there is always a "might be"
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DO WHILE .T.
ME.Work()
ENDDO