XiFi Sound Cards

Anyone here have any experience with the new XiFi sound cards? I have seen and read quite a bit of hyperbole about this cards. I am not an audiophile by any means, but people are saying that XiFi sound cards are a real revolution in computer sound. Some go as far as saying that it can markedly improve the quality of sound coming out of even very bad speakers.

Perhaps there are some sound experts out there who can help shed some light on this. As I have noted in several places I am looking at putting a new system together down the road. Often circumstances dictate my speakers are turned off. This means when building systems the built-in soundboard has always been enough.

However if this is some kind of real revolution I want to be able to intelligently consider my options when it comes to getting a dedicated sound card.