The 6-foot-6, 283-pound Williams officially became an unrestricted free agent and the most coveted defensive player on the market on Tuesday afternoon. The franchise's career sacks leader missed most of last season with a torn chest muscle, but McNair knows the Texans will have to compete with several teams willing to offer Williams a giant payday.
Williams made just over $15 million last year.
"We want Mario. We'd like to have him," McNair said Tuesday. "Unfortunately, other people would like to have him, too. It depends on how much they're willing to pay."
"We have limitations that constrain us, and we're going to do everything we possibly can to keep it there," McNair said. "We've got a lot of guys we'd like to keep. We're trying to keep that core group together as best we can, and that's our focus."
"We've got a quarterback that we think is sound," McNair said. "We think his foot is going to be fine. He's got a great arm, and he can take us to a championship. We have other issues that we have to deal with."
McNair says he's skeptical about Manning's health after the star quarterback missed last season to recover from multiple neck surgeries. He thinks other teams may be taking a gamble by signing Manning, who'll turn 36 on March 24.
"As he says, he's 80 to 85 percent healed, or healthy," McNair said. "You don't know if he'll get to 100 percent. There's a lot of risk they're going to be taking, because they can't work him out. I hope he's healthy, I hope he plays. He's a great asset to the league."
"We beat him when he was healthy," McNair said, "and we'll do it again. It's up to us. We play a lot of good quarterbacks."
The release of Winston was unexpected. The 6-foot-7, 302-pound Winston, a third-round pick in the 2006 draft, started 87 consecutive games for Houston since becoming a starter during his rookie season, and he was one of the team's union representatives. He was due to make $4.5 million this season.
McNair spoke with general manager Rick Smith on Monday night about making the agonizing move. Winston was a stalwart for one of the league's best offensive lines. Houston ranked second in rushing (153 yards per game), and the line helped Foster top 1,000 yards for the second straight season.
"You're releasing someone who's been a good teammate and worked hard, and helped get the team where it is today," McNair said. "You hate to see that happen. Right now, for salary-cap purposes, that move had to be made."
The left-throwing Leinart, the 2004 Heisman Trophy winner, played in only two games for the Texans after signing with them in September 2010. He finally got a chance to play after Schaub broke his right foot, but Leinart dislocated his left shoulder in the first half against Jacksonville on Nov. 27.
Leinart thanked McNair and the team on his Twitter account.
"I will miss the Texans fans and most importantly my teammates," Leinart wrote. "I have no time to get down, focus is on getting healthy and being ready to go again!"
Vickers appeared in 14 games, but started only one in his only season in Houston. He played his first five NFL seasons with Cleveland.