The reason it won't work on XP is because Vista's driver system is vastly different to XP's. This is the cause of all the driver confusion on launch day... Also if you remeber, Direct X is a way of communicating to the hardware via software... so the complete redesign of this means that the entire architecture is different as Netburst is to Core. Still both are compatible... they are both x86 and both processors...
Now before you say Dx10 is bad, then take a look at the first Dx10.1 designed game... As stuff matures it gets better... the next version of Dx based on 10 shall be better and so and so forth. Vista SP1 closed the gap between Vista and Xp so much its only about a 5fps or less difference on average...
Now before you accuse me of liking Vista, I don't hate or prefer it. My first installation of Vista was nice a pleasant, a huge step from Xp installation. Now my second install on my HTPC (wanted Vista media centre) completely died on me due to the fact my Vista installation was supposedly fake... I lost one itunes activation that day.... =(
Now before you say Dx10 is bad, then take a look at the first Dx10.1 designed game... As stuff matures it gets better... the next version of Dx based on 10 shall be better and so and so forth. Vista SP1 closed the gap between Vista and Xp so much its only about a 5fps or less difference on average...
Now before you accuse me of liking Vista, I don't hate or prefer it. My first installation of Vista was nice a pleasant, a huge step from Xp installation. Now my second install on my HTPC (wanted Vista media centre) completely died on me due to the fact my Vista installation was supposedly fake... I lost one itunes activation that day.... =(