Possibly but probably not. If you're legal, another words you have a legal
copy of XP, there's no point in doing it and doing so will leave you open to
the possibility that at some point you won't be able to activate or get
updates. Activation is simple and easy, an automatic part of installation.
It's nothing more than a handshake between two computers over the Internet.
Ordinarily, it will take you less time to activate than it did type in the
CD code. You can activate XP as often as you want on the same computer.
If you change enough hardware, instead of Internet activation, you may be
asked to make a phone call. In that case, simply inform the operator of
changes you've made and you will be given a new code over the phone.