I would like to standardize the answer to all questions forever more on GS. These generic answer come from feeding all previous answers on any questions in GS into a computer to compute a generic catch-all reply that can be used to save readers the hassle of sifting through threads.
It depends on your system:
The Mac OS is better for music. Vista is horrible. XP was golden. Windows 7 looks promising. Macs are overpriced. You get what you pay for. Choice is good/bad. Jobs is a bastard/hero. We don't mention Gates... ever.
It depends on your sound card:
You can really only depend on anything made by Apogee. RME users get a pass, but that pass comes with a sneer behind your back. Any other sound card is completely invalid. If you use anything else, it's like tying a cup and a string to an A to D converter.
It depends on your firewire chipset:
If it isn't TI, you must get a comp that has the TI chipset and retest before you can even ask the question.
It depends on your DAW:
They all sound different. They all sound the same. ADC means nothing/everything. Null tests decide all/are irrelevant.
It depends on your experience:
Everyone else here knows more than you. You asked the question. By default, you are on the lowest rung on a ladder full of urinary incontinent gear enthusiasts, myself included.
It depends on all your other gear:
Your gear sucks. Ours is always better and we know exactly what we're doing with it, unless you follow the link to our music we left in our sig. Then you'll discover what I did in 1986: Buying the butterfly pants, bandanas and zippered jacket still didn't mean that I could breakdance.
If you need a tie-breaker:
Ask Lagerfelt. He's the nicest guy on here and offers great advice in a friendly manner.
And for balance:
Search for Shanabit. He calls it how he sees it and isn't afraid to play the gadfly.
So using the above matrix, I must come to the conclusion that unless you're playing your mp3s on a mac through a TI chipset through Pro Tools or Logic, you're likely to damage your system. Oh, unless you used waves plug-ins to master the waves/aiffs before the conversion. Then you're probably okay. But of course, if you didn't pay for the WUP... oh, I almost forgot. Reaper looks promising. Look into it. It really kicks the llama's ass.
Btw, I'm only having fun. I enjoyed the question and ALL the responses. I even learned a bit.