how do i partition the hard disk if im installing rhel for the first tim e on the system which is already running on the windows server 2003 with out disturbing the existing os pls reply to his question as soon as possible.

During the install you are given options to use the entire hard drive or just used unused space. Do NOT choose any option that overwrites existing space.

Of course you should make a backup of the Windows stuff before starting just in case you do something wrong.

Also most folks use up the entire drive when installing Windows so you may not have any unused partition space available for your install. If so you'd want to look into doing something like resizing the Windows partition before you start. Doing a search for gparted and windows resize should lead you to instructions for that.

You can not install Linux while Windows is running. You will have to reboot and then install Linux. Partitioning can only be done if the hard drive is not in use. If you do not mind taking some system resources, you could use VMware to setup a virtual machine to run a desire OS while an OS is running.

Only UNIX like operating systems has a way to install other UNIX like operating systems while it is running through the use of chroot.

What about "unetbootin"?

That program makes an image file to create a LIVE Linux boot drive with either USB or hard drive, but it does not install Linux.

I think by "running" the OP meant "installed". Presumably he knew he had to reboot to start the install of Linux.

By the way you're not entirely correct. One can install VirtualBox from Sun (similar to VMWare) on the Windows desktop and then create a virtual partition with a copy of Linux. I haven't done it myself but a guy sent me an email once mentioning he had done this with Fedora.

I do not recommend VirtualBox because it is not reliable and stable to be used for production systems. Since VMware has a free version, there is no point using VirtualBox. Also VMware has more features than VirtualBox and VMware just works. Yes, I have tried VirtualBox.

A virtual partition in Windows is not a partition but a pointer. It uses the utility subst to point a drive letter from a directory. The problems using this method is it will not save Linux permissions if the drive is not formatted as NTFS and ACL is not enabled. Also not all programs behave the same when using this feature.

Both VMware and VirtualBox creates real partitions even though they are creating virtual machines. The virtual machine can be converted into a real machine by placing them on a real physical hard drive.

This is not entirely correct. The Ubu's have been able to do this for several iterations thanks to Wubi.

I am not particularly an Ubu fan nor a Wubi fan, so spare me the lecture on their shortcomings, which are indeed manifold.