Let's look at the the stats, sweetcell (and I LOVE to have this debate with my Mexican friends who simply can't comprehend a gringo who knows footie).
The Mexican National team has made the quarterfinals of the World Cup twice in their "long, illustrious" history and BOTH times it was when they were the host country (they enjoy a distinct advantage playing in The Azteca with the altitude, smog and flying bottles of urine).
When they are not the host nation, they've never made it past the second round, getting bounced by the likes of Bulgaria (94) and the US (2002). Not exaclty on par with Germany (98) and Argentina (2006)...
They qualify every year (much like the US) because they play in the CONCACAF region, which is weak - very weak. To illustrate - only 10 of the 40 teams in the region have EVER made the World Cup, and 6 of those have only done it once. It's been dominated by the US and Mexico for some time.
But the real problem for Mexico is that they've reached a platuea while the one advantage they've had over their larger and wealthier northern neighbor has shrunk to a near embarassment (the US is 13-9-8 in it's last 30 games against Mexico in the last 20 years, with all but one of Mexico's win coming in Mexico).
So there you have it. They're not better than the US, and I'm quite certain few will argue that the US play real soccer. Both teams are quite ugly to watch....