According to my "Star Trek Chronology", the 'Romulan Wars' ended in 2160 with the Battle of Cheron, a humiliating defeat at the hands of 'Earth forces'. I guess the Vulcans could have helped Earth during this war. It only says that Earth forces won that particular battle, and that Earth fought the wars, but it doesn't say they did it alone. 'Balance of Terror' TOS is the source of this.
However, the UFP was formed the following year, and this is only about 10 years after the events in 'Enterprise' so this war could not last 100 years.
On the other hand it says that Klingon first contact occurred in 2218, when we saw it happen in 'Broken Bow' ENT.
But, I thought then, and I still think now, that he was referring to the Vulcan Reformation or Time of Awakening. At the time of Surak, Vulcan disidents who still clung to warrior ways left Vulcan to form the Romulan Star Empire. Previous to this exodus they had engaged in terrible and destructive wars, using the terrifying weapon of war known as the 'Stone of Gol' -- 'Gambit' TNG.
This all happened about 2,000 years ago, so a hundred year war between Vulcan and Romulus would be possible. Difficult though, I expect, since neither seemed to have Warp capable ships at the time.
I expect that ST:Nemesis will throw some light onto this.
