That is one beautiful theme. It reminds me of an Imago theme, though I get the impression this is farily customized.
I confess, I love that little sprinting smiley face or whatever that guy is in the upper left corner.
Visually, it's all beautiful. No one would ever say you have a bad looking site... it's completely professional.
I looked at it in IE 5.5 (the ugly browser) and Firebird... your site looks great in both. My Firebird does not come with flash pre-installed, you might consider alternate navigation for non-flashers. Depends who your target audience is.
OK, now some gentle criticism or suggestions.
1. Font sizes. I must be blind or something, but small font sizes are simply too much work to read. I understand they look subtle and nice... but, much of the web is a reading medium... making it difficult to read slows down the user. However, I recognize that designers must love them, since so many people use them... pity the poor users.
I also recognize that in your columns, you want tight control, so maybe you need pixel precision there.
I think a reasonable compromise is to allow the user to adjust the text sizes in their browser. To do this, you use variable text sizes in your CSS in areas where you are willing to give up control. Perhaps for content in the center column. If you set your text size as 100% instead of 10px, it will allow the user to adjust to their liking. Alternatively you can use keywords, like small and medium, though I like percentages for some reason.
2. The "MENSAJES Y SALUDOS" block is showing up with scroll bars on the right and bottom. If you can find a way to eliminate the scroll bars... or, at least the bottom scroll bar, I think it is perhaps easier to use.
But, if you didn't change anything you would still have a wonderful site. The above are just a couple of suggestions.