How can I do remote desktop connection in Linux (RHEL 5) server with Windows (Windows XP) clients?
How can I take full rights? (I know the administrator password.)
I want to access all things in the client machine, I even want to install software. How can I do it?
It looks like your asking to RDP FROM Windows TO linux?
You want to install xrdp on the linux server. I don't know if there are packages for RedHat specifically (I was able to simply apt-get install xrdp on Ubuntu 8.04), but this will let you use MSTSC from a windows workstation into linux.
If you are doing this to remotely admin the linux machine, you may want to consider brushing up on command line usage, and use putty + ssh. SSH is the 'usual' way to admin a linux server.
Install VNC ( vnc-server is the redhat package name) on your linux server. Configure it to use root user and password. Install VNC client on your windows machine. Enjoy full ROOT remote access.
VNC is a good tool, but not in any open or work environment unless you encrypt it. There are VNC servers and clients that support this but you can do it using an ssl tunnel.
Firewall off the normal VNC ports, then open an ssh connection with a tunnel from your workstation/tablet/whatever. I use putty for this. So long as the tunnel connection is open you can carry on working.