You'll need a proper disk management utility. I recommend Partition Magic 8.0. If you do it properly you should be able to alter your partition settings without losing your data. Just make sure you know what you're doing.
Barton 2500+, 512MB Corsair Platinum XMS 3200 CL2, Radeon 9700, WD Raptor 10,000 rpm S-ATA HDD, Asus A7V600, Enermax 460W SilentPlus PSU.