X-Fi isn't a rip. There are cards from anywhere between $70 and $400 dollars - the difference in quality is mainly the input/output modules, and the software you get with it.
If you get "XtremeAudio", which is the cheapest, you get the 24-bit sound, X-Fi Crystalizer (guesses missing frequences - pretty cool), and 5.1 sound input, mic, and line in/out.
You can then go to "XtremeMusic","XtremeGamer", or "Xtreme" standard chipsets - they have the same input/output plugs but include extra software and EAX 5.0. Look at the individual cards to see their advantages.
When it gets expensive, you are buying F1delity and Elite Pro, or "Extreme" versions of xtremeGamer/XtremeMusic like remote controls, and external modules with lots of inputs/outputs, and stuff like 64mb X-RAM on the chipset.
For a small budget, you WILL get a good sound quality difference if you upgrade to XtremeMusic, or XtremeGamer standard. That's a good price, and a good set of features. I noticed a huge difference when I had to take out my XtremeMusic card out and suffer the onboard sound card.
Regards
Rhys