You can't use NTFS for Linux. Linux is capable of reading NTFS partitions, but it cannot write to them yet. So you need to re-partition your hard disk (I assume you already have Windows installed using all the space on your hard disk) to create enough space for Linux. You can use tools like Partition Magic for that.
Why do you want to use RedHat 7.3?
It's very old. Why don't you use Fedora Core 4 if you want to stick to a RedHat based distribution?