I bought my first sound blaster sound card about 15 years ago. It cost me about $180 on sale. It was much better than the sound on my 486sx 33 Mhz. The sound card was not only better, it was necessary because the computer didn´t have sound
I now use a computer a built a year ago:
Asus P5GD2 Deluxe 3.0 Ghz
2 gig kingston ram 533 DDR2
etc.
etc.
etc.
For me, the sound on the motherboard is great!. I have a good pair of headphones. I use the computer for a little of everything: Web, games (sound is very good for me), listen to music etc.
My advice, don´t get a sound card. Use the $60 for a better quality PSU, a better quality case with good ventilation or a better graphics card. You can always ad it later but if you buy a cheap PSU, case or power supply you are stuck with it.