What about DOS? The deal with DOS is that one is loading a virtual floppy called A: into extended memory and then booting from this floppy. So you have to capture an image of a bootable DOS floppy first. Some more details can be found in the mknbi-dos utility.
I have booted DOS (both M$ versions up to 5.0 and DR versions up to 7.03) diskless this way. A mknbi-fdos is available for building tagged images for booting FreeDOS, the procedure differs slightly from booting M$ or DR DOS.
If you were thinking of booting a Windows machine via the network, it seems (I'm not masochistic enough to do this) the problem is not the network booting but the mounting of a file system over NetBIOS (Windows does not do remote mounts of root filesystems over NetBIOS on TCP). So that rules out a Samba server. It appears to be possible over a Netware server, for which Linux or FreeBSD has workalikes. Also it is said that only certain versions of Windows will allow diskless booting. You will also have problems with pathnames and the usual Windows hassles. Do you really want to do this? You do know that you can run lots of desktop applications like Netscape, StarOffice, etc. on Linux, FreeBSD, etc. now? Why pay good money when you can use equally good free replacements? Anyway if you are still determined, in the Etherboot home page, there are links to external Web pages, one explaining how this was done with a commercial TCP/IP boot ROM, another explaining how to do it using Etherboot and Netbios over IPX. A recent user experience is here. Good luck and send us your experiences or better still a URL to a page explaining how you did it.