I'm going to go ahead right now and say that I am a Die-hard Yankees fan, and thus very Anti-Red Sox. But I'm not willing to say that the Red Sox World Series win in 2004 is void by the fact that Manny has tested positive for Steroids. Here is Manny's stat line from the 2004 World Series.
1 HR, 2 R, 4 RBI, .412 BA
The Red Sox swept the Cardinals that Series, and it wasn't even close. The Red Sox team ERA of 2.50 had far more to do with their Victory then Manny Ramirez, who was given the WS MVP Award. Not a single hit of Manny's decided a game in the World Series. So sorry Yankee fans, they stil get credit for winning 2004.
He was even less of a factor in the Red Sox 2007 World Series win. He drove in 2 runs in the first game (Sox won 13-1), but was invisible for the rest of the series, authoring this stat line for the Series.
0 HR, 2 R, 2 RBI, .250 BA
Again, Manny had nothing to do with the Red Sox winning the World Series.
So Manny had nothing to do with the World Series victories themselves. But what about how the Sox got to the Series. The Red Sox won all 4 of their games in the 2007 ALCS in Blowouts. So while Manny had 2 Home Runs, both actually came in losses. He had 10 RBI, but that wasn't enough to say the Sox won because of him. It was more the heroics of Josh Beckett that got them to the World Series. The Sox swept the ALDS that season and none of the games were close.
As for the 2004 ALDS and ALCS, it was much the same. Manny batted .382 with a Home Run and 7 RBI in the ALDS, but the Sox swept and most of the wins were blow outs. Manny did not decide the victory. Manny was less of a factor in the ALCS, where David Ortiz was the one who led the Sox to victory.
So as much as Yankee fans everywhere want to say that Manny using steroids voids those World Series wins, they don't. The only thing you could say is that maybe the Yanks win the division in 2007 instead of the Sox, which could possibly change the playoff matchups. But unlikely.