Irrelevent comparison.
The 90's Cowboys should be compared with the 70's Steelers, teams that were absolutely dominant over a short period then began a slow decline.
The 00's Patriots are more like the 80's-90's Niners. Both teams have had dominant stretches. For the Niners, the 88-90 stretch was one of the most dominant periods any team has ever enjoyed, and the 94 team also stands as an all time great.
Our Patriots are eerily similar, they won a premature super bowl with a young quarterback, an old guard of vets, and spare parts. They experienced a stretch of unparalled dominance (the longest winning streak in history). Now they trot out a total juggernaut, deep in every aspect of the game.
What these teams have in common is the "lean" years in between. The Patriots have been in contention every season since 2001. Even if they peak now, and lose vital pieces in the coming years, they have several years of contention in them.
As far as Dallas goes, the Patirots have not maintained that level of talent and dominance for 4 CONSECUTIVE years, like the Cowboys did, but this 2007 team could give any of the INDIVIDUAL Cowboys teams of the 90's a run for their money.