Vista is the future, thats true. But for the next few years, Vista 32Bit is the future, not 64Bit. (most of the programs are 32bit not 64bit so they don't gain anything)
Because hardware makers don't have actual drivers and using modded ones means not signed and not signed = won't install.
If you are creating a game to run on 32bit and 64bit its a little more tricky anyway because many stuff is a little different (sizes of numerics as the most simple thing - int and float bit is always OS one - but the whole security system is on a far higher level on Vista64 as well... so this will need a fair amount of extra work. Not just compile and run everywhere. Thats only "possible" with visual studio 2005 with enabled 64bit compatibility flag)
But basically: yes it will run. how good and what works depends on what you took into consideration when creating the code.
Because hardware makers don't have actual drivers and using modded ones means not signed and not signed = won't install.
If you are creating a game to run on 32bit and 64bit its a little more tricky anyway because many stuff is a little different (sizes of numerics as the most simple thing - int and float bit is always OS one - but the whole security system is on a far higher level on Vista64 as well... so this will need a fair amount of extra work. Not just compile and run everywhere. Thats only "possible" with visual studio 2005 with enabled 64bit compatibility flag)
But basically: yes it will run. how good and what works depends on what you took into consideration when creating the code.