Do you have PXE boot setup? how are you booting from Network? Let me know if you need help seting up PXE Boot services.
Without it network book will not work the way you are tying to boot. Yes, your PC will get a an IP address on the regular network from windows, but that has nothing to do with booting from NIC/LAN there is alot more to it then just plugging in the network cable and expect the Laptop or any computer to boot.
If you don't want to set up PXE booting then your other option is to use what SysExpert says regular network boot disk which can be created using the Ghost Boot disk Wizard.
Let me know which route you want to take...