Generally, you can only have one PXE environment as machines will send a request and the first server to respond would win.

That being said, I know in the 6.x versions, you could to MAC filtering (i.e. if you have a list of MAC addresses of equipment you do or don't want respond to, you can have it respond or not respond to that list).  It would either be that, or having the different platforms only respond to specific VLANs (the iphelpers would help in that scenario).

Each DHCP scope in your environment can direct to one PXE server (either the DHCP server itself or another machine).  If you use the iphelpers correctly for DHCP booting, you could direct each subnet to a different PXE server if you chose to do so (or, if you wanted to get really creative, you could have one PXE server listening on multiple IP addresses to had out different default boot files).

Really, as long as your DHCP server is only responding to requests from the subnet your clients are on, you won't have any PXE related conflicts.  If your using iphelpers, this should be easy.

Hope this helps.

Joe

In 6.x you could set a delay on the PXE response for multiple PXE environments.  Not sure if this is available in 7.x.

There isn't a delay response in 7.x.  Do a search for "PXE modes of operation" in connect or techsupport and read about PXE Force mode, that is probably the implementation you want based on a DHCP scope like Joe suggested.

Nelo