There is little or no gaming available without the use of emulation or virtualization.
There is no support for Xen in Solaris 10, you will have to Nevada to get that which also means no XP apps unless you can get them to run in Wine.
It is unlikely that windows only hardware will be supported.
You could say Solaris has been around the block a while.
Not sure where "gaming" fits into "professional desktop".
If you want wide ranging device support, eg USB cameras etc, then I would say go for some Linux distribution.