A fresh install is best, so if a problem arises you will know it's not a result of left over files.
I doubt you will notice a difference between the 2 drives, but I think the 640 gb may be a fraction faster as it only has 2 platters, you would probably need drive speed check tools to know for sure.
Just checked WD site and the 640 gb is faster but I doubt you will notice in actual use.
Until Windows 7 goes gold on 22 October, all you can do is a fresh install...
Not correct - The OP can use his Win 7 .iso to upgrade his Vista installation. 7 will definitely recognize and the upgrade option will be available. Having said that, he will *not* be able to upgrade an RC build to the RTM/GA one. So if he wants all his programs and data to be migrated to his Win 7 install, I would recommend imaging Vista over to the new drive first. Then upgrade the image.
disconnect the drive that you wish to keep all of your info. w7 is very nasty are destroying things without the users knowledge. only install first on a small drive and then merge everything over.
I personally give up w7 for other software compatibility issues. some of the wxp software will not work at all under w7.
install it at own risk.
well i not sure about that but
i have w7 partitioned on the same drive as windows vista but i would do a fresh install and keep vista just in case theres problem and then buy it on october 22 and upgrade
unless you find a problem with ur hardware or software thats not compatible with 7