SteadyState for Win...if you want to be 100% sure.
Cleaning up cookies, custom browser settings might help but if you like to be 100% sure and tried to follow the new cookie-standards, here's a good-old method:
1. Install a fresh copy of win
2. make the necesarry steps to secure your pc.
3. install steadystate.
voilla!! , now at every restart you are a new-born child.
The complete step-by-step guide to get back to selling today!
It's a bit of hassle to constantly re-verify the account - guess it's ok if you are really for not changing through accounts, but otherwise pretty bothersome.