Regarding VNC server,
we have had good experience with the NoMachine NX server,
and I recommend this. Have onse site where it works very well on a 
network with 10/100 access to the desktop.

http://www.nomachine.com/

The NX server has recently been released for no cost (ie free as in beer).
The desktop clients, which are for Linux, Windows, MacOSX, and Solaris
have always been free.

I would recommend this to anyone to try out - instead of using 
Hummingbird etc. on your Windows desktop you can get a full remote 
desktop on your Linux cluster for free.
And if you need to access your cluster over a mobile phone link, it 
compresses very well.

I realise this can't be bundled with Scientific Linux, but its just a 
download form their site and an install.


-- 
      John Hearns
      Senior HPC Engineer
      Streamline Computing,
      The Innovation Centre, Warwick Technology Park,
      Gallows Hill, Warwick CV34 6UW
      Office: 01926 623130 Mobile: 07841 231235