Sorry for the delay in replying. My advice is the same as that given by nr, only a bit more wordy.
Putting a desktop environment onto a SheevaPlug is possible, but will come at the cost of a significant consumption of drive space, and could also require a few technical hoops to be jumped through. We understand the desire to ease oneself into linux (most of us went from Windows power users to linux dummies), but now is the time for you to take that step and - honestly - it's not so difficult.
Here's why the alternative - of installing VNC - is still a big hurdle:
Firstly, you need to install X and packages that it depends upon. Then VNC. The former has every chance of creating new headaches for you. As an alternative to VNC, you could go for
nomachine, which many prefer. However, there is no ARM version of nomachine but there is a compatible open source server. And
that would be another big headache for a linux newbie.
On the other hand, webmin simplifies many administrative tasks and presents itself in a browser, so although this might not be the graphical interface that you asked for, it is mostly very user-friendly. So we recommend that now is the time for you to bite the bullet and use a few terminal commands.
Here's how you can install it:
(if necessary)
apt-get install wgetDownload the .deb file:
wget http://prdownloads.sourceforge.net/webadmin/webmin_1.500_all.debInstall it:
dpkg --install webmin_1.500_all.debAnd see the dependencies mentioned in nr's post.