Is there a 64-bit port of the original software for windows? The download page on the Bitcoin site lists two clients for the windows platform. Both clients are a 32-bit binary. 

Running a 64-bit build of Windows on a multi-core processor, I find myself wondering whether a 64-bit binary exists. So ... Is there a 64-bit port of Bitcoin-Qt for Windows out there?
Short answer: no.

Long answer: It's not likely to be necessary for some time. 


There are still a considerable number of people on 32-bit Windows (~23% according to the Valve Hardware Survey, which paints a good picture of forefront computer enthusiast hardware, so the market share is likely to be larger among non-gamers).
Bitcoin-Qt doesn't yet push the limits of 32-bit memory address space. On my machine, Windows 7 64-bit, the program is consuming only ~128 MB of RAM while downloading blocks (haven't sync'd in a while). On my Mac, it's about 240 MB.
The type conversion necessary may be prohibitive, if there is significant code written specifically for win32. Qt itself is obviously working fine on 64 bit, as is the most of the bitcoind codebase. There may be things here and there to work out. 
More likely to be prohibitive, or at least "not worth it", is the management of the release of another package. There's already five packages managed, so including another is just that much more.