Hi,...
to make a partition you have to (VISTA):
START--> find MY COMPUTER and right click on MY COMPUTER Icon (menu will appear)---> click on MANAGE --> you will see STORAGE and click on DISK MANAGEMENT!
there you will see all your HDD's ... RIGHT click on HDD which you want to do a partition (menu will appear) --> and click on SHRINK VOLUME!
wait till PC checks how many GB available for partition!
then in "ENTER AMOUNT OF SPACE TO SHRINK IN MB" put as many MB you want for partition! you'll see how many available above in same window!
1000MB = 1GB
10 0000MB = 10GB
Then click on SHRINK!
then you will see that you HDD now has UN ALLOCATED HDD --.right click and NEW SIMPLE VOLUME!
follow instruction on screen and that's it!
Thanks