hi,
at the begining, a better way to learn and experiment linux (redhat or any other) could be to use VMWare software, in which you can install other operating systems, without having to deal with partitions and other complicated things.
in VMWare, you do not have to make a dedicated partition for linux.
you can just install linux in VMWare and test, whatever you want to.
you can download a trial version from their website. you can also google to get an adequate tutorial about installing linux on VMWare.
a pentium 4 with 512 ram is sufficient.
once you feel yourself comfortable with linux usage and it's installation procedure, you can resize your computer's hard disk partition with proper software and install linux properly.
regards.