I know this thread is old by now, but I just wanted to mention that iSCSI support can be added to WHS! I am currently doing just that. I use the StarWind iSCSI SAN - Free Edition on WHS. It doesn't have many limits.
You will need to download the Microsoft iSCSI Initiator from here:
Then you will need to download the StarWind Software from here:
(choose Download under Free Edition)
Afterwards, you will setup the software on the WHS server. You can do this by using Remote Desktop or by using Advanced Admin Console. Once everything is set up, use the StarWind Installer on one of your other computers to install the management console. Then connect to your server and start using iSCSI. The default user/password is root/starwind.
For me, iSCSI is invaluable because it allows me to run diskless workstations. Windows 7 has native iSCSI support for installation, and I use a combination of TFTPD32 Service Edition on WHS, DD-WRT on the router, and rom-o-matic.net to do net booting. For more information about setting up network iSCSI boot, go here:
The information is old, but still works just fine.