Well for one thing there are no VNC packages that do RDP. RDP is a Microsoft protocol used by Remote Desktop and RDESKTOP and derivatives and clones. VNC is different, based on code that began its life at IBM. (Thanks guys.)
1. Did you check that VNCSERVER is running on the RH workstation?
2. Are you using VNCVEIWER from the Windows machine?
3. What behavior do you get from VNCVEIWER?
4. Have you extracts from any logs from VNCSERVER?
The telnet test from Linux to Windows tell you nothing, because that is not the connection you say you are trying to make.
The telnet test from Windows to Linux means something, but only if the VNCSERVER is running on the Linux box. (Telnet and vncveiwer can only connect to a service if it happens to be running.)
Once you are sure that VNCSERVER is running, if you still get no connection try turning off the firewall and test again. If you can then connect, you need to retune your firewall rules. IF you STILL cannot connect with the firewall down, then run netstat -an and look for listeners and figure out where VNCSERVER is listening and what connections it will accept.