daveny5

My guess is that to upgrade to Win 7 I'd probably also have to upgrade my system as well. So, we're talking at $400-$600 for the minimum configuration to run it. 

Not necessarily, however, I recommend you run the Windows 7 Upgrade Advisor before upgrading. Changing operating systems is not something to do without planning and preparation. 

+1 !!
 
I'll add a couple more recommendations -
Be sure to download all your key system component drivers (video, network adapter, etc.) for Windows 7 to a separate disk, and back up ALL your data folders (including browser links, e-mail data folders, etc.)
 
Even though it can be a bit of work, I personally recommend a "clean" install when upgrading the operating system, versus upgrading on top of the old operating system.
 
As I learned the hard way when I was in the business, if you upgrade on top of an existing operating system, it's not unheard of for some system-related issues to migrate from the old O/S to the upgrade O/S, and it could take a while to diagnose...