No DirectX 10 for XP

Now I'm not much of a PC gamer, and Microsoft just helped reiterate my reasons as to why I'm not, upgrades.
As most people know Microsoft is releasing within the next year or so a new OS, code-named Vista this OS is supposed to bring some great things to the table for PC gamers, one of which is the new DirectX 10. I get the impression that PC developers love to work with the newest stuff and this really could create a situation where not only are users going to need to upgrade they're video cards but also an OS, it will not be far off that games will be released that require DirectX 10, and anybody not running Vista will be left in the cold.
This again is the primary reason why I miss out on all these great PC games, upgrading. With consoles I know it's a 5 year lifecycle, and it'll cost me about 500-600$, with PC's the lifecycle appears to be shorter and I spend as much on a video card as I could for a console.
And to think I thought Sony gave a big slap-in-the-face to it's base after E3, this sure seems like one from Microsoft now too.