Computer Audio Questions...

As of right now I am wondering as to how I can improve my sound setup for my computer.

As of right now I have a Sound Blaster Audigy 1 Sound card (SB0090) in the comp which is 5 or so years old, but still runs fine. I have creative 5.1 Inspire 5200 speakers. My audio is from games and from .mp3's ripped at 320 Kbps. (I know I should switch to a better lossless format, but .mp3's work better for everyone because of .mp3 players and my phone uses .mp3 etc etc, so .mp3 is used for convenience.) I also have a budget Altec Landsing headset for use when my roommate is around.

I am looking to upgrade my sound system and I am at a stand still as to what to do. I spoke with one of my friends and he said that my speakers were fine and I would not notice a difference except for high sound levels. We decided that I could use an upgrade to the sound card. I am confused as to which model to get. I would need a 5.1 or 7.1 card (what isn't 5.1 now right) I have been looking at the Creatives. I also would prefer something that will allow me to use my 5.1 speakers with my xbox 360, Digital Optical Input I'm thinking? I cannot decide which is better. The X-fi chipset cards, or the Audigy 2 ZS, or an Audigy 4. The Audigy 2 has a higher sample rate then the X-FI. I am at a standstill as to which card to get, so I would like some clarifications on cards and some examples of what I should get. ($80 to $120 price range preferred, but other price bracket suggestions more then welcome.)

I am also looking for a good pair of headphones for courtesy use. I also DJ for my college radio station and parties, so I would like something I could use for 3.5mm and 6.3mm (I have a 3.5mm to 6.3mm adapter.) that would sound good but not be a huge investment. ($80 max, but again I'll accept suggestions from any price bracket.)

I've read that the Klipsch ProMedia Ultra 5.1 speakers are amazing, but I don't know if they are justifyable price wise compared to what I have now.

I thank all of you for your time.
~Cell