Yeah - a good soundcard makes a hell of a difference.
I dont think this is really relevant, but;
Standard laptop soundcards tend to pick up noise relatively easy, especially if you have your powersource plugged in. I was picking up hard-drive noise as well, which is sortv a constant high pitch through the speakers. Right fucking paing in the ass. I found that i could remove of most of this noise by removing the ground pin on the laptop power source and any external hard-drive power supply i had connected. Its pretty rungi i know, and wouldnt reccomend it to anyone inexperienced with mains voltage stuff.
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As for soundcards, i had an external m-audio firewire audiophile, and i noticed an instant change in sound quality (you can easily tell with good speakers). All my songs on NG have been made using it too. But, as there are only rca outputs on the back of the card, the cables which went directly to my monitors were quite prone to picking up stray noise (and i have goood rca cables). I could go into further depth about the bad side of things if you want, but overall the m-audio external soundcard was much better quality than any internal stock cards ive used (on my old laptop, and the one on my motherboard atm).
Although, now im using an m-audio 192 pci soundcard, which i have just recently bought - it has balanced outputs, a very high sample rate (192k) and good bit-depth (24 bit). The balanced outputs are awsome, because they cut out any noise picked up in the cable from the card to the monitors (and i noticed an immediate improvement - in both sound quality and noise-rejection). Although, if youve got a laptop, this card wont fit - it goes into a PCI slot on pc's. Just look for a card with balanced outputs (if your monitors or setup can utilize balanced inputs).
What ive said above is sorta biased towards that shitty thing called noise, but yeah, overall getting a recording based soundcard is a good, good start. haha