I have xp on my first hard drive and I installed ubuntu 12.04 onto a second hard drive drive. I left some unallocated space on that second drive that I would like to convert to a ntfs partition. Using g parted would I just select the unallocated space and convert it to a primary partition?
(Unedited answer to original question that only mentioned 'free space' ; later edited to specify it was in fact 'unallocated space')
Even though there is a certain ammount of free space on a drive, it doesn't mean no files are located on the outside portion of your disk where you'd like to create a new partition. Simply put free space gets fragmented and what you see in GParted or any other partition editor is just a chart that represents the percentages of free and occupied space on each partition.
What it means in practice is that creating a new partition in your case will involve some data movement thus putting the whole operation under the risk of data loss*, so make sure you make a backup copy of your most important data before you proceed.
* Some operations done by partition editors require the partition editor to move some data around. In such a case there's a risk of data loss in case of e.g. power loss. The risk of data loss due to factors other than power loss and partition editor crash is very small. It's fastest and safest to perform partition operations on a clean disk.
The procedure to get what you want in GParted (I recommend using Parted Magic bootable USB/CD): 0. Back up your data*
1. Resize your existing partition leaving X megabytes of free space, where X equals the intended size of your new partition.
2. Create the new partition in place of the unallocated space you got after completing step 1.
Creating new partition on a disk with free space involves some data moving done by partition editor*, while creating new partition on unallocated space does not involve data moving - creating new partition on unallocated space is hassle-free and instant.