Just looking at the remaining games and I think the Cardinals have a huge advantage with their remaining schedule. This in contrary to what a lot of people predicted when they said September schedule favored the Reds.
They start with the Fish today who have been desimated with injuries then they go to the Pirates (the only team the Reds have been able to beat in a series this month), they finish the week against the Cubs but now Colvin is hurt. They still play the Rockies but it is the last games of the season and if the Rockies are not in contention then they will probably not play their better players.
The Reds on the other hand start with a Brewer team that can flat hit and score runs, this is not good for the Reds because they have been scoring around 3 runs a game. Will not cut it against the Brewers. Then off to SD, where the Pads play well at home and once again not a place a lot of homeruns are hit and lately it seems the Reds are scoring via the HR ball or not scoring at all. They finish the year with the Astros and Brewers and we witnessed what the Astros pitchers did to the Reds this past weekend.
With that in mind I think advantage goes to the Cards. Now I know the Reds have a 6 game lead, but it is really 5 in the loss column and the Cards are playing against teams that they can sweep the series where the Reds are going to struggle to win the series. I think the Central title will not be decided until the last weekend. Hopefully it turns out better than 1999.