Can you partition hard drive with OS installed already?

Hello.
I got 500Gb hard drive and I have created only one partition "C:" on it, then I installed Windows XP SP3.
Now I downloaded Windows 7 Beta, and since it is beta, I don't want to lose any of my existing files, therefore I want to partition my hard drive even more.
I want to add partition named, let's say, "E:", then install Windows 7 on it.
Can I do it even though I already have Windows XP installed on my only partition?

Not without a partitioning software such as Partition Magic. Or you can run that OS on a virtual machine. Read the below thread to get an idea of what Virtual PC is:

http://discussions.virtualdr.com/sho...d.php?t=236373

edit

In Vista this works. In XP it doesn't. Anyone using XP's disk management to repartition a drive already in use, could mess up that working OS.

thanks for clearing that up photolady i didnt mean to give wrong info, you might want to delete my post before he does something wrong

i edited it

That's ok, freddy. We all make mistakes at one time or another.

Ok, i actually forgot 'bout this post after first photolady's reply.
But the thing is that it worked great with partition magic 8.
Now Im running Win XP and W7, but I like 7 more now.
Too bad they're shutting down the beta soon.

i like 7 also very much a lot faster and just seems easier to work with

ztein--the latest information I can find says the beta will shut down on August 1st--that's not too bad.

Ye I know.
Hope they'll release the actual version soon after the beta closing.