Heh maybe I worded it wrong. I know you can't do a straight upgrade, you would have to do a fresh install.
I was just saying you don't have to format it thats all. I have lots of files I don't want to get rid of, and save games.

Also I know about the memory limits of 32 and 64 bit, but I don't really want to risk buying memory and then have it not show up because of the memory address allocation problems.

And FYI my housemate also does this for a job, and I study computing extensively. I have my facts right thanks.