Having just DHCP/TFTP and SYSLINUX is not enough for being able to PXE boot/install "any" bootable ISO out there. Take a look at Serva (I'm related to Serva development) starting here
http://vercot.com/~serva/an/WindowsPXE1.html
and continuing here
http://vercot.com/~serva/an/NonWindowsPXE3.html
You can see there how to automatically PXE install MS Windows OSs and also how to install Linux distros and boot the live versions of them. You can eventually reproduce what Serva does with your favorite PXE server.
You can also see Microsoft WDS and MDT but they are just focused on MS OSs.