Its possible to enable Direct 10 effects in Windows XP for Crysis. I have only tested this on the single player demo and it was worked really well.
“The difference between ‘high’ settings and the tweaked settings is immense: shadows are deeper, more realistic; the leaves have better reflective properties, better textures; the colours are better; and the level of detail is simply stunning.”
To do this all you need to do is:
Tweak the configuration files in \CVarGroups\ (usually located C:\Program Files\Electronic Arts\Crytek\Crysis SP Demo\Game\Config\CVarGroups)by copying and pasting the ‘very high’ settings (1st paragraph) IN PLACE of the ‘high’ settings (last paragraph) the game will load the highest possible settings even though the drop-down menus display ‘high.’”
Then when you load the game go into Settings; System and select High to choose the new video settings.
I have included a link to my patched files in case you have trouble; copying and pasting them over yours (making a backup of yours first of course) should in theory work but I have not tested this yet.
Download my DirectX 10 Windows XP Crysis files