Yes you can just move your C Drive over to your external and then copy them back 1 at a time.
The only difference from Pro and Ultimate is Bitlocker and being able to use more than 1 language.
$299.00 and $199.00 sounds like they may be a Home vs Ultimate version or it could be a Full version and OEM version or something like that.
Would need more info on what they are saying.
I'm assuming that 7 can be formatted onto my "E" drive partition, but what becomes of the Vista OS? I was told I could have both Vista and 7 on my PC, but I don't know why I would. I am one who actually liked Vista though.
You can have both but you might find that Win 7 is good enough, also keeping multiple OS's on a system can be a lot of extra work keeping them all up to date.
Make sure you have all the Laptops drivers before starting, some Laptops do not have 64 bit drivers for there mobo.