1.) It's rather foolish to claim that Dooku's force reserves were "depleted". Neither the film or the novelization allude to such. In fact, any time Dooku's level of force power diminished(which ONLY happened when Anakin bombarded him, btw) he was able to open up his being and gather force energy from throughout the universe to replenish/boost him:
"[Dooku] called upon the Force, gathering it to himself and wrapping himself within it. He breathed it in and held it whirling inside his heart, clenching down upon it until he could feel the spin of the galaxy around him. Until he became the axis of the Universe. This was the real power of the dark side, the power he had suspected even as a boy, had sought through his long life until Darth Sidious had shown him that it had been his all along. The dark side didn't bring him to the center of the universe. It made him the center. He drew power into his innermost being until the Force itself existed only to serve his will."
"[Dooku] gathered the Force once more in a single indrawn breath that summoned power from throughout the universe; the slightest whipcrack of that power, negligent as a flick of his wrist, sent Kenobi flying backward to crash hard against the wall."
"With all the power that the dark side can draw from throughout the universe, Dooku[...]"
Thus when Anakin went 't3h z0n3', Dooku was still at his peak levels.
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2.) The part of the novelization in which Dooku "needed" the guards to intervene is non-canon, because it does not mesh with the film.
Excerpt from the novel:
"With a shout of the Force, he shot like a torpedo up the stairs behind Skywalker, and Dooku decided that under these rather extreme circumstances, it was at least arguably permissible for a gentleman to cheat. "Guards!" he said to the pair of super battle droids that still stood at attention to either side of the entrance. "Open fire!" Instantly the two droids sprang forward and lifted their hands. Energy hammered out from the heavy blasters built into their arms; Skywalker whirled and his blade batted every blast back at the droids, whose mirror-polished carapace armor deflected the bolts again. Galvened particle beams screeched through the room in blinding ricochets. Kenobi reached the top of the stairs and a single slash of his lightsaber dismantled both droids."
The film's depiction of said events:
http://www.youtube.com/watch?v=kmIkpRkgaZk
(starts at 1:26)
As you can see, Dooku never shouts "Guards!", nor does Anakin block any blaster fire from the droids in the film. So again: the novel's description of that portion of the battle isn't canon.
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3.) Kenobi was a complete non-factor during that battle. Dooku casually dismissed him(in both the novel and film) each and every time he entered the fray. Heck, at one point Dooku blocked the simultaneous strikes of Anakin and Kenobi with a single-handed block of his own(implying that he was stronger than two level 8's):
That said, the [only] reason Anakin won is because he was able to tap into a great portion of his 'Chosen-One-Christ-Power' while, most importantly, maintaining clarity of mind-- and that clarity of mind in conjunction with focus of his raw power is why beginning-of-film/'t3h z0n3' Anakin>>end-of-film Anakin/Vader.
"But Palpatine's words rage is your weapon have given Anakin permission to unseal the shielding around his furnace heart, and all his fears and all his doubts shrivel in its flame. When Count Dooku flies at him, blade flashing, Watto's fist cracks out from Anakin's childhood to knock the Sith Lord tumbling back. When with all the power that the dark side can draw from throughout the universe, Dooku hurls a jagged fragment of the durasteel table, Shmi Skywalker's gentle murmur I knew you would come for me, Anakin smashes it aside. His head has been filled with the smoke from his smothered heart for far too long; it has been the thunder that darkens his mind. On Aargonar, on Jabiim, in the Tusken camp on Tatooine, that smoke had clouded his mind, had blinded him and left him flailing in the dark, a mindless machine of slaughter; but here now, within this ship, this microscopic cell of life in the infinite sterile desert of space, his firewalls have opened so that the terror and the rage are out there, in the fight instead of in his head, and Anakin's mind is clear as a crystal bell. In that pristine clarity, there is only one thing he must do. Decide. So he does. He decides to win."
Anakin may have started that battle as a level 8, but by the time he unlocked his Christ Power and killed Dooku(who, again, was amped with universal force energies) his skillset, and overall power as a duelist, had increased to the best we've ever seen in SW, imo. That's why I, personally, put him over the likes of Yoda and Palpatine as a swordsman. He was Godly.