I did the same with Dell last year when I ordered my XPS M1330. It came with Vista + MS Works (at the time they had no pretend Linux alternative - with lower specs and same price as a Vista laptop).
I wrote to Dell for a refund and enclosed a printed out screenshot (via digital camera) of me ticking the "I reject license" on Vista bootup and another screenshot of Kubuntu running on the laptop.
A month later I was refunded £120 + vat for both Vista and Works. Not bad considering the laptop cost £520 - minus M$ Tax = £400.