If you are only going to use the sound card in analog output then go with the X-FI. The Razr has some features you wont find on the X-FI, just like my Meridian. PCPerformance Magazine did an excellent review on my card, the Razr, and the ExtremeGamer.
The review was geared to gaming so my card scored a 6 out of 10. The Razr was 8 out of 10 and the ExtremeGamer was 9 out of 10. They reported better music/movie sound quality out of the Razr and Meridian. Both of these cards can do real time Dolby Digital output for games and what not through the optical output... The X-FI can't. If you only game and wont be hooking this up through the digital outs then the X-FI will give you the very best gaming performance. I was more geared at sound quality and use with the optical output.