How to transfer to new PC

Hi,
I had to urgently replace my laptop, will be receiving it next week, and I would like to know how I transfer the license to the new laptop. There is one major difference. Whereas now I am running under Win XP Pro 32bit, the new laptop is a win 8 Pro 64 bit, and of course would it be great to switch from Opus 32 to Opus 64 bit, if there is any difference in versions.
If you could please give me the procedure to follow.
Thanks

Simply download the 64 bit version from www.gpsoft.com.au and install on your new machine using your existing license.