Thanks for your reply, Rob!
a)
Type of computer: PC
OS: Windows 7 64bit
NIC: Realtek PCIe FE Family Controller - I don't currently use this network card since I'm networked wirelessly, but from the device manager, WoL is supported and enabled
Wireless Network Card: Ralink RT2500 - From the little I've managed to scrape up on the internets, there doesn't seem to be WoL capability for this device. Correct me if I'm wrong, I would love to keep this solution wireless if possible.
Auto-login: Enabled. Not sure what is meant by an autostart mechanism.
b) I'm no audiofile. Radio quality would suffice.
A: Nil for network programming experience. I have taken a couple of university level data structures and algorithms courses, and I have done a bit of playing around in various languages.
The ethernet shield definitely seems appropriate for goal (b), but do you think I could get away with less if all I want to do is broadcast a magic packet? Maybe just an antenna?
Maybe I'm very misguided in thinking it could be so simple. I know nothing about networking, but if I need more hardware just to broadcast a signal, I'm curious to know why.