"VERY LATE last night, Donovan McNabb declared that the Eagles' stunning signing of Michael Vick was, "no different, really, than bringing T.O. here."Because, you know, that turned out so well.The Eagles, controversy-free lately, rejoined the circus last night. The big top opens at 11 a.m. today at NovaCare, when Vick is introduced at a news conference. McNabb and Eagles coach Andy Reid were very clear on their reasons for taking on the responsibility of sponsoring Vick's return to the NFL after 18 months in prison and nearly 3 full years away from football, following his conviction in an ugly dogfighting scandal.Both McNabb and Reid spoke evocatively of the importance of forgiveness, of second chances. They were less clear on exactly what Vick is going to do to make this worth the bother to a team that now might be pushing past pickets to get to practice; the gist seemed to be some sort of prospective "Wildcat" role for Vick, to which McNabb indicated he was willing to cede a few plays here and there, in hopes one of them would be a big gainer."This is America," Reid proclaimed. "We do make mistakes." The 29-year-old former Pro Bowl quarterback deserves "a chance to prove he's doing the right things," Reid added.In the middle of the second quarter of last night's preseason-opening, 27-25 loss to New England, with some team officials even apparently unaware of the most momentous development of an eventful preseason, word leaked out via ESPN.com that the Eagles had signed Vick. The ESPN.com report said a 2-year contract; Eagles president Joe Banner, confirming the signing to the Daily News, said 1 year plus a club option for a second. Fox Sports said Vick will make $1.6 million this season and as much as $5.6 million in the option year.NFL commissioner Roger Goodell has said Vick will be eligible to play in the final two preseason games, so his Eagles' debut could be Thursday, Aug. 27 at the Linc against Jacksonville. Goodell has said he then will rule on a regular-season suspension, which could be anywhere from nothing to 5 weeks.This morning's press conference is scheduled to be attended by Vick, former Indianapolis Colts coach Tony Dungy, who has served as an adviser, and representatives of the Humane Society. Vick's first practice with the Eagles is expected to be tomorrow, Reid said."Everybody we talked to said the same thing," Banner told the Daily News, "that [Vick] was remorseful and had gone through an incredible transformation, that he was basically good at heart. We heard this over and over again from people who felt he deserved a second chance."Banner said the team and Vick agreed to terms about 48 hours before the news broke.During his postgame news conference, Reid repeatedly referenced the drug-related troubles of two of his sons. "