Windows 7: Can I create a partition in a (used) external hard drive?

I have a 1 TB hard drive that is being used a lot. The format is NTFS or FATS, (sorry if those are not spelt correctly) windows hard drive. Anyways - there is like 400 gig spare. Can I simply go in and use gparted or something similiar and make a partition for a linux backup (which is ext4)

(I know this is a windows forum but u guys are the best! You are all v informed)

So basically from your experience if I do this is there a strong chance that the data on the drive will be hosed if I introduce a linux partition?

Thanks a lot

Yes indeed. If you don't have an internal hard drive portable case, just power off your computer, hold the power button in for a minute to discharge all electricity, open the case, plug the older hard drive into the IDE or SATA cable for a secondary hard drive, (keep the case open to watch all fans), plug in the power cable, press the power button. The system will see the old hard drive and assign it a driver and may want to reboot; that's OK. Now after reboot, go to Windows Manager (Right click computer, choose Manage). Choose Disk Management, point at the older hard drive, right click your mouse and choose Format. When prompted, choose NTFS and format the entire disk. When it's done.....voila! You now have a second internal hard drive that you can use for backing up an Image of your C: Drive (Highly Recommended) and for storing all kinds of files like music, videos etc. rather than keeping them on the C: Drive and filling it up. (see image)

Thanks for your reply - very good of you.

Just to make sure though, that the drive I am referring to is an off the shelf External Hard Drive of 1TB.

Does the above still apply - ? Thanks