I own an X-FI XM and Xonar on PCI, their both decent cards. Xonar has and advantage when it comes to music, but with a potent amplifier the X-Fi can be very near. I've seen a lot of people claiming that Xonar compared to X-Fi offers a huge difference when it comes to music, but I find this more like the Placebo Effect. Yes it's better for music, since it has higher quality components but but it's a small difference only felt by true audiophiles and proper equipment (AKG 701, BD DT 880 Pro, Grado SR 80, etc...). But even they have use an amplifier to make it worth wile.

As for gaming, if you moved to Vista EAX is pretty useless since Alchemy is more like joke then a capable software to get EAX run on Vista. I had problems with all kind of games, were the game sounded worst with Alchemy (rain, foot steps sound was missing), then with out it, even crashing because of it. I personally don't use EAX on Vista and don't recommended either since "Vista killed EAX" and XP is a dieing OS when it comes to games.

If you can keep the old card and have to buy a new one. go with Xonar. The primary sound for all games runs great on Xonar, same goes for X-Fi, or even some integrated chips, on the other hand EAX is an alternative sound which is emulated by Xonar and runs native on X-Fi, but being useless with Vista (as mentioned above) you can't take it for granted as a bonus or feature, more like a pain in your ears and hart for spending money an a useless feature. Let's not forget Xonar is real great with DTS and that might be the future of gaming, since it works just fine on Vista.

So yeah, my recommendation is: Forget about EAX and go with Xonar since it's more capable then X-Fi. You might even go for a PCI version since most PCI-e slots are badly positioned on most motherboards. Most people that hate Creative will tale you the same, but I'm not doing it from same reason, you have above the right motives. I personally never had BSOD, related to my sound card. Usually that's a problem related to poor designed motherboards incapable of handling PCI cards the right way. It's true that there were some X-Fi card with problems, but most of them have the motherboard as the primary source (and no, it's not just with some nForce 4 - since with some worked just fine, yer this problem reappeared on other boards even with Intel chipset).

Most people that recommend X-Fi (if not all) never used a Xonar, that's the only thing they used so that's the only thing they recommend. It's more like a Fanboy thing, or come to think of it - that's exactly what it is . I personally was a little disappointed with Xonar since it didn't give me that huge difference that I was expecting based on some opinions, which now I know - they come from Creative haters. But, putting that aside, Xonar is better - so why waste money on something that's not that good when it comes to quality (build and sound), just because it has a useless feature like EAX?

PS.On XP - EAX sounds great, it's a shame M$ didn't offer a better alternative for DS. But that's a lost cause which Creative desperately tried to revive with Alchemy, to bad they didn't succeed the right way.