PXE BOOT file for MAAS nodes?

Hello:

I'm setting up MAAS and some nodes using VMFusion on MacOSX. I have built the MAAS server and 3 nodes, however they are not commissioning.

My question is what do I use for the pxe boot file?

I'm letting VMWare handle the DHCP for my virtual subnet, and the config looks like this:

subnet 192.168.221.0 netmask 255.255.255.0 {
 range 192.168.221.128 192.168.221.254;
 filename "pxelinux.0";
 next-server 192.168.221.3;
 option broadcast-address 192.168.221.255;
 option domain-name-servers 192.168.221.2;
 option domain-name localdomain;
 default-lease-time 1800; # default is 30 minutes
 max-lease-time 7200; # default is 2 hours
 option netbios-name-servers 192.168.221.2;
 option routers 192.168.221.2;

I've just guessed for the filename of the pxe bootfile, and I can't see where you document what to use.

THe nodes DO boot into something, but they pause for a long time before going to the login prompt, and they never commision so that I am unable to complete the juju bootstrap- I just get:

dillera@maas3:~$ juju bootstrap
2012-05-10 00:34:41,355 INFO Bootstrapping environment 'maas' (origin: distro type: maas)...
Unexpected Error interacting with provider: 409 CONFLICT
2012-05-10 00:34:41,483 ERROR Unexpected Error interacting with provider: 409 CONFLICT

So, what pxe boot file should I be using?