Not unless you've already made a number of hardware changes and the
RAM upgrade pushes the limit. Here are the facts pertaining to activation:
Piracy Basics - Microsoft Product Activation
http://www.microsoft.com/piracy/basics/activation/
Windows Product Activation (WPA)
http://www.aumha.org/a/wpa.htm
If activation does turn out to be required, you'll be so prompted.
If it's been more than 120 days since you last
activated that specific Product Key, you'll most likely be able to
activate via the Internet without problem. It shouldn't require more
than a couple mouse clicks.
If it's been less than 120 days since you last activated that
specific Product Key, you might have to make a 5 minute phone call. The
number will be provided. The process is normally quite simple and
painless.