There is many ways to test iSCSI connection to VMware ESX Server. Sure that there is many different free software which can be used as a shared storage (OpenFiler , Free NAS, EMC Celera (VM) , Xtravirt). It seems tha one of the most popular way is to setup the connection with an Openfiler. Few days ago there is another guide which just appear from Xtravirt. Now you can really test and connect your ESX Server environement different ways and using different tools :
01. You can use VMware Workstation and configure Openfiler VM inside and test the connection to your ESX Server via iSCSI (My way). I Just published it as a PDF guide too You'll need 2 physical boxes.
02. You can use physical box for your Openfiler, exemple on Simon Seagrave's Blog. You'll need 3 physical boxes.
03. You can do it Xtravitrt's way and use direcly the ESX Server's local storage and download it as a Virtual Appliance for your physical ESX Server. You'll need 2 physical boxes (one for management workstation or laptop).
Sure think that using 3 physical boxes split the job and the performances are better, but not everyone has at home 3 physical boxes, right? And for learning the setup it's just great. Then in the real environment you might use iSCSI or Fibre channel SAN… but that's another story…