Are you looking to trial LANDesk before purchase or have a lab that replicates your live LANDesk environment for testing purposes? In either case the right setup should mirror in some way the environment you are trying to support and its complexity is limited only by the needs you have and the resources you have available.
In all cases I wuld recommend a Virtual Server for your core as it is ideal for quick rollbacks after testing. The same should be true for a selection of your client machines as quick rollback is essential. For physical test machines make sure you are able to rebuild them quickly to a known build (decide if you want clean installs or snapshots of a live image as clean is slow but clean, snapshot is fast but can have issues such as expiring domain coimputer accounts).
Above all make sure you know what it is you mean to test and document how you plan to test it. No good throwing resources at a test lab without planning how to use it. So overall, if your test lab is representative, quick to setup and quick to reset to a known state then you have a good lab.
P.S. Don't name your test core server the same as your live server unless you known these systems will never be on the live network and if your are on a private network, don't forget you will then need to replicate your AD environment for truly representative tests.
Mark Star - MarXtar LANDesk Enhancements
Home of Power State Notifier & Wake-On-WAN for LANDesk