I'll back Sarah on that. I find the first install disk for Mandriva is what I use for all partitioning needs.Never failed me yet, simple to use, and once partitions done, do a hard shut down. I use the first install disk for Slackware for erasing drives with the dd comand, dumps you in a root session really quick to get it done.
Go to this link and you will see what you are in for so no suprises.
you will go as far as the the eighth screen and choose "custom disk partitioning" instead of existing. It will bring you to a this:
When done and changes are commited, hold pc power button for 4 seconds and you are done............unless you decide to finish the install of Mandrake.
You will end up shrinking your linux partition then increasing windows partition, so windows should be fine, but linux install may need reinstall, not sure. Will be interested to find out.
*****do not format, you will be simply clicking on the colored partition you wish to resize, click the "resize " button that appears, use the slider or type size in the box, do same for the other and in the file menu, choose "commit". If you format you will be losing everything.