TheInquirer reports that the upcoming DirectX 9.0 L is simply a renamed and refurbished DirectX 10 for Windows XP. It will make DirectX 10 games to work on Windows XP.  And games such as the upcoming Crysis won't work on the existing DirectX 9.0 c. they need a DirectX 9.0 L.

One of the biggest issues is the fact that Nvidia or ATI won't have any mainstream or entry-level cards until at least mid- to end of Q1 2007. This suggests that if Vista tips up around the beginning of the year, gamers will be turned off by it. Electronic Arts, the publisher of Crysis, wants to sell hundreds or thousands, even millions of copies and we doubt that Nvidia can produce and sell that many Geforce 8800 GTX and GTS cards. It will be interesting to see whether the Windows XP Crysis will be different from the Vista ones.

Update: Now they report that they were wrong about DirectX 9.0 L. They managed to confirm the existence of DirectX 9.0L but it won't be a DirectX 10 for Windows XP. It will be the other way around. It is a faster version of DirectX 9.0 that will run under Vista only :-D

interesting