Flashbuilder 4.7 problems - Need to overlay AIR 3.1 or use FB 4.7 serial on FB 4.6

I have several projects ive developed with FB 4.6 on winxp. 

I purchased a new win8 pc since the old pc began to fail, and purchased FB 4.7 64bit for my win8 pc, I only wanted the serial which i presumed i could use to register FB 4.6, which you cant... 

I now find none of my projects developed with FB 4.6 run in FB 4.7 using AIR 3.4. (Problems are mainly embedding swfs, simple playing and stopping of swfs) 

So .. Ive tried overlaying AIR 3.1 but this does not work (win8 64 bit specific?)i cannot use the serial i purchased on FB 4.6 

Does anyone have any answers or advice please?

Ive got multiple projects which are now dead on my new pc, with my old pc about to die.. 

Ideally i want to use my FB 4.7 serial on FB 4.6orRoll back FB 4.7 to FB 4.6 somehow..is this possible? 

Thanks all 

L