Just a thought, and 'scuse me while I don my asbestos longjohns, but given the choice of both, I'd personally go Blue whenever possible.
Why? Because while the video quality may be identical now due to the dual-purposing of the HD encodings, BluRay has POTENTIAL for higher bitrates in the future, whereas it's my understanding that HD-DVD is just about maxed out now. Therefore, if only one will eventually rule the marketplace, I'd prefer it be BluRay.
If there are features that only HD-DVD offers that you'd like to see become the standard, then you ought to support HD-DVD.
I'm fairly new in this neighborhood of the forums, so if the HD-DVD people would like to persuade me into the other camp or just tell me I'm a misinformed luddite, now's your best chance. I'm still reading and learning. But keep in mind - I have not even a teensy interest in interactive features. With me it's all about how good the audio and video are.
MentalDragon raises a good point, though. There's no such thing as true purple when you purchase software that's available in both formats at the same price. At that moment, you have to decide to be either bluish-purple or reddish-purple.