Without formatting creating two drives is not safe so take backup before doing so.
Try to allocate atleast 5 GB to work on linux.You can convert u r file sys to ext 2 or ext 3.NTFS will not work.Later on you can mount u r file system by instaling ntfs drivers.
For creating and partitioning some threads are going on in Open Source section which will give you more clear idea.
Here is a link
http://www.thinkdigit.com/forum/view...er=asc&start=0
(parttioning starts fr nearly 3rd or 4th page)