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64-bit Support
Solaris has been 64-bit by default on SPARC for many years. It will also run on x86 hardware in 64-bit mode by default on 64-bit capable hardware.
There is no seperate installation media for 64-bit: both 32-bit and 64-bit software is included on the same CDs / DVD.
One thing to notice is that older builds of Solaris Express Community Edition (SXCE) and Solaris 10 will install in 32-bit mode on x86. If your processor is capable of running 64-bit binaries then the 64-bit kernel will be started once you have installed the OS.
Drivers
A major advantage of Solaris is that any driver available as a 32-bit binary is almost always available as 64-bit as well. At present however, Solaris does not have drivers for as many devices as Linux or Windows, so you are best to check before you try running it on your hardware. See the first part of "
How to Install" for some ways to check hardware compatibility.
Seems like this will run as a 64 Bit os by default if your pc is capable.