Re: tougher than it looks @phy445
I rescued one of those cases from work, and after keeping it under my desk for a year, then taking it home (by bicycle!) and keeping it under the desk there for years, I'm too committed to it to throw it away. Also I can't let my wife win this argument.
Anyway, here is someone a lot more dedicated than me who actually did the PC conversion:
http://build-its.blogspot.co.uk/2011/04/how-to-fit-your-pc-in-power-mac-g5-case.html
And at some point I will do the same ...