how to activate bluetooth file transfer in windows 7 64 bit?

It is correct that there is a slightly higher memory usage for the 64-bit versions but I think the margin is almost irrelevant (usually less than 100MB). If you look at systems that are actually running a 64-bit OS you mostly have 6GB and more RAM so the difference is around 1% or less.

With exceptions of none-optimized executables the 64-bit versions usually have a ‘smoother’ feeling to it. They seem to be more responsive and offer better performance (nonetheless because 64bits can be processed at a time instead of 32).

One drawback may be that certain features, functions or plugins may still not be fully implemented or compatible to 64-bit.

On a 64-bit Windows a 32-bit application can use 2GB memory by default, 4GB with IMAGE_FILE_LARGE_ADDRESS_AWARE A 64-bit application has set this flag by default and can use up to 8TB of memory which comes in handy especially under heavy work like encoding or video editing. http://msdn.microsoft.com/en-us/library/windows/desktop/aa366778(v=vs.85).aspx#memory_limits

You can’t. Even looking at the individual components in the package, there aren’t 64-bit versions of Apache, PHP, etc. for Windows machines. If you want 64-bit versions, you will need to grab the source and recompile for 64-bit (including any necessary debugging to make things work right).

windows 64bit drivers are not the same as windows 32bits, also some programs perhaps refuse to work properly. You will have to reinstall applications since windows 7 64bits has two programfiles directory. Best to do clean install.