The partitioning tools suck in Windows in general.
Something I would suggest is to download a Ubuntu Live CD, and burn the ISO image to a cd. Make the changes in the bios to make it boot from the CD drive. CLick on the button to "Try Ubuntu". It'll take a few minutes to fully up and running since everything has to load off CD, but worth the wait.
Ubuntu has a some great tools included. The you're going to want to use is called Gparted. you're going to go to System>Administration> Gparted. Then it's easy from there.
Put the sd card in the mulit reader slot or USB adapter. Ubuntu will auto-mount the cars, and the partition(s) You're going to have to unmount them, and use Gparted to change the size of partition(s). Keep in mind to only work on the card, and not the actualy hard drive on the computer.
In Gparted you should see the sdcard listed as something like /dev/mmcbl0p1, or /dev/USBxx. or something like that.
DON'T CHANGE ANYTHING THAT IS LISTED AS
Make the changes you want to make to the SD card make or remove partitions, just amke sure that you use all the space in the sd card with one or more partitions.
I'm not responsible for your mistakes, and I assume that you are not the average user. If this is above your head find something that knows what they are doing, and do this for you.