Yes, LANDesk would definitely be supported on a virtual server. You would need to make sure that you take into account whatever overhead your VM host requires and make sure the server is still strong enough to run everything.
Depending on how many nodes you have connecting to the server, will determine how the VM will need to be set up. I would start the VM with two vCPU's, even if the physical server has more. Depending on how much RAM is in the host, and what you have in the physical system, you can probably reduce that some as well. Of course, this is all assuming you'll be running on VMware ESX/ESXi (4 u1 I hope) and not some other virtualization hosting system. I would also split out the SQL server from the host if it's set up on the physical server right now.
One of the things you'll come to love about having a LANDesk host as a VM (especially on ESX/ESXi 4) is the snapshot capability. Take one before you install a LANDesk update, test it out, and then if it's all good, you remove the snapshot reference point. If things go sour, you can quickly roll-back to the point in time prior to the install. This is another good reason to not have the SQL server db on the core server. Since any changes made after the snap would be gone if you needed to roll back. With the db on another VM, it's not effected by the roll-back and your inventory will remain intact.
Another benefit is including the core server in a HA cluster. With that, even if the host server goes down, the VM will be picked up by another host quickly.
If you want some more assitance, send me a message and I'll help as I can...
What is the best configuration then for +/- 4000 nodes? (virtual server)...