Yes, you can designate one or part of one hard drive toward Redhat if you'd like. Redhat will install LILO (LInux LOader), and give you the option to add other operating systems (such as Windows) so you can have one prompt on bootup that lets you decide which you'd like.
Mind you, there are a huge number of possibilities of different options / configurations to do what you asked about, so don't get confused on the details. Your best bet is to do a little research on the more common ways to boot, what disk to install on, configuration, etc., and then get to it! Everyone has their own favorite way, and you just need to find what works for you.
Read these:
http://www.redhat.com/support/manuals/
(Most notably, the 7.1 Intel x386 guide)
Browse the site - they have huge amounts of docs available for you to consume.
Also, you might find usefull:
http://www.redhat.com/support/docs/tips/urls/urls.html
(Note the large security section... Pay attention here!)
http://www.linuxdoc.org/
(Read the Guides, HOW-TOs, and FAQs for more specific questions)
If you have any specific questions that you can't find any info on, please post back - Redhat is my primary distribution at home, and I may be able to help.
Have fun!
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