I do a lot of video editing, and I'm buying a new computer soon. I'm wondering if I can completely transfer my contents from my hard drive as is from my old laptop, to my new desktop. I have a seagate 1.5tb external hard drive, which is plenty of room for all my files - but will my editing programs (Sony Vegas Pro/Pro Tools 10) still be accessible on my new computer once they're transfered? Can I just transfer then begin working with my programs again, or do I have to install them again?
Most likely, you will have to reinstall the programs.
Most programs store information in the windows registry which will not have that info if you simply copy the program files.
As a suggestion, you could clone the laptop drive to a hard drive, or preferably a SSD and install it in your new desktop. Then, you would have to update the drivers for all the new devices on the desktop along with reactivating the os with the activation code from the new desktop.
This assumes that you are using the same version of windows on both the new and the old.
It's possible to transfer apps and drivers. There are a few programs floating around which will help you do it. But if the new computer has different hardware, it's highly highly recommended you do a fresh reinstall of everything. The time you waste trying to track down obscure problems and rebooting due to mysterious crashes will typically far exceed any time you save by not having to reinstall everything.
Then if I ever need something from the old computer, I can grab it by starting up the virtual machine on the new computer. If there's an old program on there I forgot to install on the new computer, I can always access it again via the virtual machine. http://www.vmware.com/products/player/
I then scrub the old machine, reinstall Windows, and sell it or give it away. This lets me "keep the old computer around" without having to keep the physical hardware of the old computer around.