Need help partitioning external drive with windows xp disc management

I want to partition a 500gb iomega external hard drive in 2 parts so i can make a backup image of my system using acronis true image,following the windows xp disk management,in step one it states to create a new partition right click unallocated space on the basic disc where you want to create a partition and click new partition but there is no new partition appearing to click only delete partition,
my question is if i delete this partition which already exists on the hard drive will new partition then appear so i can divide it in 2,i have never done this sort of thing before so maybe someone with experience will guide me through this,thanks in advance for any assistance.

 

If your having that much trouble with it you might want to download partition magic and use that to break down your HDD

 

SRH22, thanks for your reply but i wanted to avoid using another program to do the partition,

 

ddp,
The drive is new,thanks for your reply but i took a chance and deleted the existing partition and then new partition appeared so i went ahead and carried out the partition i required,all solved.
thanks for your assistance.
dermotk