Hung out in #LTSP on irc.freenode.net and got it working, here's the recipe:
Clear out your dhcpd.conf for the option-128/129 junk, you don't need it there. You do need to set the IP there, however.
browse to /tftpboot/lts/pxe/pxelinux.cfg/
if all of your client machines use broadcom, you can edit the default file, otherwise, convert the ip of each client to hex (use http://hesketh.com/schampeo/projects/ipcalc/ , remove the leading 0x, and copy default to a new file named the hex of the IP. The file should be in all caps. client 10.0.0.10 => 0A00000A)
at the end of the append line, add a space and then NIC=b44
restart yur dhcpd (/etc/init.d/dhcpd restart) (only if you had to change /etc/dhcpd.conf) and reboot, and you're good to go! I had to mess with video and sound afterwards, but hey!