Debuting as an 18-year-old for the Adelaide Crows, McGregor played a few solid games in his first season. He picked up 18 disposals in his first game, as well as 6 marks and a goal. He then went on after a few more solid performances to play the rest of the season. He averaged 8 disposals a game for the season, as well as an aggregate of 5 goals. For the next couple of seasons, McGregor struggled to find his spot in the Adelaide team. He played 14 games in 2000, averaging 10 disposals. But, he was inaccurate, kicking 9 goals, 15 behinds. In the 2001 season, McGregor found his way into the Crow's backline, played 12 games. He had lower stats then his last season, averaging just 9 disposals, and kicking 3 goals for the season.
2002–2003 seasons
McGregor did not play the first 5 games of the season, but came back for the Crows sixth against Richmond. He still came into the match with an injury, and failed to pick up any touches. When he returned, he played mainly down back, but sometimes when a match-up wasn't there for him, he drifted forward as another big forward. He averaged 12 disposals for the season, kicking 5 goals, including 2 in a semi-final against Melbourne. In 2003, McGregor found himself changing roles between back and forward again. He missed out on just two games for the season, including their first final. In all, he played 22 games for the year, having 12 disposals and 4 marks a game. He also kicked 6 goals for the year.
2004–2005 seasons
When Neil Craig took over as coach of the Adelaide Football Club, McGregor has started to play some of his best footy. He only missed out on the last 3 games of the 2004 season due to injury. During 2004 he was described by Brisbane Lions star forward and enforcer Jonathan Brown as the toughest opponent he'd ever had to play on. He was pushed forward earlier in the year by Gary Ayers, proving his prowess by kicking 5 goals in a game against Richmond. He averaged 13 disposals a match, and kicked 12 goals. He continued his good form into the next year, missing out on just one game of the year. He played his first seven games down back, before Neil Craig shifted him into the underscoring forward line. It proved to be a great move by the new coach, as McGregor went on to kick 31 goals for the season. During the 2005 preliminary final against the West Coast Eagles. McGregor was the victim of an elbow from Travis Gaspar, just before the bouncedown. This resulted in a 50-metre penalty and Adelaide kicking the first goal. Gasper was charged with striking, but found not guilty due to it being deemed an act of self-defence.
2006–2008 seasons
was a solid year for McGregor. He played in 19 games for the year, kicking 21 goals. McGregor only played nine games in 2007, leading him to request to be traded to another club at the end of the season. He was retained on the list, and continued to play in 2008. However, despite being contracted for 2009, he retired at the end of the 2008 season, having played only seven games.
