with your budget you might be a little hard pressed, but here's what I'd do....
Sell the creative card and get a GRUB DAC. You can build one yourself for under $30ish, buy a built one for more. If you can build then I'd also build a miniMax, or a Max and include the GRUB in the enclosure. This combo will run you under $300 for parts (if you go all out will be about $500 in parts...) Then look for a used pair of Senn HD580 or HD600. You should be able to find a pair for $200 or less. This is at the upper region of your budget, but selling the sound card will help offset the costs.
do you happen to have a link of where to purchase one of these Max? or a kit? I want to do it myself but i dont know where to start.. If it's a night and day difference i will let me budget go up to 800$. will that open more doors?