Installing system challenge

I've got a new PC beside me. It doesn't have an optical drive. I need to get an operating system onto it. I'm on a mac.

---
I set the bios to boot from USB CD/ROM and hooked up an external DVD drive. Popped in a dvd with the windows seven ISO burned onto it. (used disk utilities /restore to put ISO onto DVD)

No luck, "LOADING OPERATING SYSTEM..." but the DVD drive is silent as a mouse, it's not doing anything.

-

So I set the BIOS to boot from USB ZIP (I'm doin OK for a guy who's never had a PC eh?) I use disk utilities to reformat my flash drive (one partition/Master Boot Record/OS Extended) and then again to restore the Windows ISO onto the drive.

-

Didn't work. Tried Formatting it as MS-DOS, didn't work either.

-

Ahhh the joy of a new PC.. any ideas?