Yes, Budget is the key here, plus knowing what you have, will also help to know what you are upgrading from...Not worth getting a new card if you are not actually upgrading.
The X-FI might be a bit OTT if you are not really needing to go all out, and will be a complete waste of time if you have naff speakers, and if this is the case, then you probably wont find any benefit from any other creative card.
I have a fairly stupid number of sound cards, and many many creative ones, and one thign is true and that is, that there isnt really all that much difference between a basic Live card, and an Audigy 2 ZS... Not really... So, if you are only neeing a fairly good gaming card, then look around for the cheapest you can find, a SBLive24 is the same as an Audigy LS and thats perfect for the price, this is 7.1 and I have a couple of them in my kids PCs and they are great.
Now, IMHO Creative cards are gamer cards, and nothign more. if you are after, more realistic audio quality for serious work, then the Creative X-FI seems to have that edge that has been lacking in previous cards, I myself dont think this is true, and its just yet another card in the long & large list of creative cards that cant quite make it out of the Game card arena, and oyu might want to look towards the Voyetra / Turtle Beach or Philips side of things, which OCUK dont seem to be selling anymore, but a friend has a HiTec which really sound very nice with the right AMP/Speakers.
I personally feel, that creative, while brilliant cards, give a fairly harsh sound, while my Philips and Turtle Beach cards, give a much warmer, and realistic sound. Obviously as I said previously, this is dependant on the speakers I use.