Hello FarquahrWindsor,
marcus what does ubuntu install if you just hit guided?
It will only set up the disk partitions (/boot, swap & /). You'll still have to install at least the OpenSSH server from the Tasksel menu (optionnal but recommended).
Once everything is done, you may "sudo apt-get update && sudo apt-get upgrade" your installation prior of installing Zentyal (or anything else).
Regarding the S*lusVM partS*lusVM comes in 4 flavors: OpenVZ, KVM and both Xen environnements. I would recommend to make sure that it is a fully virtualized environment (like KVM).
Also, depending on your service provider, chances are that your Ubuntu install comes from:
a) S*lusVM Template Network
a1) Minimal (nano won't be there)
a2) Complete (like if you were installing Ubuntu from an official ISO)
b) Regular Ubuntu ISO
On a side note regarding service providers;
They are generaly using there
local Ubuntu repo list in order to have faster updates and save bandwidth.
Best,
Marcus