How much RAM does your computer have? If you don't have at least 4GB then moving to 64-bit is not a great idea. The number one reason to move from 32-bit to 64-bit is to give you the ability to access more than 4GB of RAM.
The windows7 licence covers the choice of 32-bit or 64-bit. I've reinstalled 64-bit win7 on machines that came with 32-bit using the same product code to reactivate it.
If you bought the retail version, then you get both dvds in the box.
I think you can do it with Laplink PCMover...
Laplink Software - Support - Forums - View topic - Windows Versions
Depending how much memory you have you may need to add more to run 64 bit. Minimum should be 4 GB. Oops just realized this info was already provided and cannot delete post. Sorry.
How much ram do you have? If you don't have at least 3GB it would be pointless to go for x64. Which are those apps that refuse to run under x86 (32 bits)?
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