cfdisk is also good so is parted, but if you never have done this before reading the RHEL4 manuals and the manpages helps greatly.Anoher solution is to use gparted for this, gparted is a GUI tool for doing this.
Screenshots:
http://gparted.sourceforge.net/screenshots.php
Check and make sure you have the rpm-build, parted, pyparted-devel and pyparted rpm packages installed then download the gparted-0.3.3-2.fc5.src.rpm source rpm file from Fedora Core 5 extras here;
http://download.fedora.redhat.com/pu...xtras/5/SRPMS/
And install/build the package (as root);
rpm -ivh gparted-0.3.3-2.fc5.src.rpm
cd /usr/src/redhat/SPECS
rpmbuild -bb --define 'dist .el4' gparted.spec
cd /usr/src/redhat/RPMS/<arch>
rpm -ivh gparted-0.3.3-2.el4.<arch>.rpm
It is up to you to meet the build requirements if any. Watch the output from the rpmbuild command to know exactly where the binary rpm package is (the <arch> parts).
And please read the RHEL-4 manuals, download them and have them hardy for reviewing, they actually answer the vast majority of questions asked.
http://www.redhat.com/docs/manuals/enterprise/
.