"but then it accepts it and reboots and then goes through the process all over again, so the machine never properly boots up!" are the machines trying to activate themselves?
You have installed an NIC, have you copied the.inf and .sys files for the network adapter to the RemoteInstall\Setup\Language\Images\Dir_name\i386 folder?
Are they OEM? if they are then it can be that you might need a volume License CD with the appropriate VL agreement. A VL versions of Windows XP does not have a Product Activation requirement.
Whats eventvwr.msc throwing up? if its The Operating System Image You Selected Does Not Contain the Necessary Drivers for Your Network Adapter. Try Selecting a Different Operating System Image. If the Problem Persists, Contact Your System Administrator.
Theres another but I doubt its relevant click here