tokala
Emperor
With an all-new system and >=4GB RAM, i would suggest to go with the 64bit version. There shouldn't be any driver issues anymore, unless you want to use some ancient scanner or something like that.
Although 64 bit applications are not yet common, some games, or at least some hardware hogs (like Civ5, E:TW, Supreme Commander) either are large address aware or can be flagged as such and will than be able to gobble up 3 GB instead of 2GB before crashing due to insufficient memory
There is a way to make this work on 32 bit systems too, but it might have negative side effects.
Although 64 bit applications are not yet common, some games, or at least some hardware hogs (like Civ5, E:TW, Supreme Commander) either are large address aware or can be flagged as such and will than be able to gobble up 3 GB instead of 2GB before crashing due to insufficient memory

There is a way to make this work on 32 bit systems too, but it might have negative side effects.