This is partially correct. Yes Windu got played, but GL has stated that Windu won the Lightsaber duel. Which means that Windu is a better duelist than Sidious. Now if Sidious did use his full power, Windu wouldn't have a chance.
Windu > Sidious - Lightsaber
Sidious > Windu - Force Power
It's only partly correct. If you want me to go in-depth over it, say so.
I just realized something.
1. We know that Mace is a better duelist then Sidious.
2. We know that Qui-gon, Dooku, and Yoda where all equals in lightsaber combat with Mace at one time.
If this is so, I guess Sidious isn't so special with a lightsaber (obviously he makes up with this in force beastliness). Perhaps I'm thinking through this incorrectly, but does this mean that Dooku is a better duelist then Sidious? That just seems crazy to me.