Well, it is definitely BS marketing.... but you have to admit it was effective!
Go back 2 years on these very boards, and nobody would have considered anything ATI made, except for the All In Wonder if you had the need. That deal with Valve helped make ATI acceptable to some, especially those who hated them with a passion for their crappy drivers.
I came damn close to getting a 9600XT myself, and some it was that voucher.... in the end, I chose to stay with that which hadn't disappointed me and grabbed the 5900..
I'll buy Half Life 2 when it comes out, either way.. if it runs like crap, I'll go back and play DooM3 again.... perhaps it's first, possibly second, expansion pack by then:P