Windows Vista Home Premium 64-bit with SP1 preloaded, Intel® Core™2 Quad Processor Q8200
8GB DDR2 memory
640GB Serial ATA II hard drive (7200 rpm)

I'm using xp on all my other computers. I use some open source software like open office and some free opensource video stuff (like to convert youtube to avi).
Some music powertracks pro, OMB some of the free utilities.

My question is about the Windows Vista Home Premium 64-bit, I have no idea about 64 bit. Do I need to know anything?
Will all of my old software still work? Most of it?
Will McAfee still work? (I get it free with my IS)
Thanks