Sony :: Upgrading HD On Vaio Z

I made the mistake of falling for a CTO Z590 and not getting the specs I wanted, which included a 320GB 7200rpm HD instead of the slower 5400.

So, specs online indicated that a Scorpio Black was the right drive.

I've gotten it and have seen the steps on how to mechanically replace it.

My question, however, is advice on how I should go to transfer my data and switch OS.

I currently have Vista Business, 32-bit installed. I would like to go to Windows 7, 64-bit and then bring over my data. Going to 64-bit requires a full install.

Since I am going to switch over to the new drive as my internal drive, is it possible to swap the drives, install the new windows OS on a partition on the new HD, put the old drive into the external HD, and then transfer at my leisure files from the old HD on the new internal HD?

I'm a bit paranoid that once I disconnect the current HD, my data is at risk. Is this silly, or can I upgrade the way I just described?

Also, what are the benefits of partitioning my new drive for the OS as opposed to having everything on one partition?

Finally, the Windows 7 I have is still a Beta version and I have heard that if I install this version, come September of next year, I will have to do a full new install of a production version. Is this true? If so, what W7 64-bit version is available now? I don't mind paying.

I've been putting this off for a long time (have had the new drive sitting uselessly for over 2 months). I'm deployed to Iraq, so have no way to backup my data other than burning some DVDs and if I break something, no repair facilities.