There is a possibility that the Windows 7 installer provided by HP is a clean copy of Windows 7. But as Kari says, you cannot install 64bit from your 32 bit environment.
Is there an Upgrade activation key in the package it came with? If not, then it is doubtful it will activate since activation will likely be linked to the HP Vista key tattooed to the mobo.
If you want to try it and your Vaio can run 64 bit per usual, make a backup image of your Vista (stored externally) then try booting from the Windows 7 disk and see if you can wipe the drive, format and install 64 bit.
Let us know how it goes.