Can I install Windows on a diskless system with iSCSI?

No need to reflash your firmware or pay for a software solution, especially if you need to boot only one computer. The solution is: gPXE + iSCSI initiator plus some cooking. Most of what you need to do is explained here: http://www.etherboot.org/wiki/sanboot This works for Windows XP to 7 and for Server OSes too.