I'll admit that I'm not a huge gamer (And it sounds like you are). I don't have a either an X-box or a PS. My main concern on the matter is only due to the format Blu-ray or HD. Whether one is better than the other when it comes to gaming, online-gaming and so on I don't know much about. But isn't the X-box 360 more than a gaming console? Isn't also a dvd-player, a mediacenter and sofort?
You know way more than me when it comes to gaming... no doubt about it. And X-box might win the gamingwar. But IMO they'll never win the HD vs. Blu-ray battle - Never!!
And hey... I havn't read one of the marketing docs from SONY that you refer to. I was at the IFA-fair in Berlin and saw only Blu-Ray (Toshiba as an exception). Other than that I've read a few articles... and a few of the standard marketing propaganda docs from Microsoft ;-)
Maybe HD will win when it comes to games... but I seriously doubt that they'll have any success other than that.
But please, by all means... invest your money in HD. I'll invest mine in Blu-Ray and see a crystal clear image of HD dying.