The main protocol that shuttles information around the Internet, TCP, has built-in error detecting mechanisms. Thus, the MP3 files you download won't have transmission errors. However, they may be degraded by being low bitrate MP3 files, which can throw away a significant amount of the underlying information that you would have been able to get from the CD (if you're using a lossless format such as Apple Lossless or FLAC). Whether it sounds significantly different is a whole other discussion.
There are some websites, such as magnatune.com, which allow downloading in lossless formats (FLAC), in addition to MP3 files. For these websites, you don't lose anything in data quality by downloading it.
Something else to compare is the price of a used CD (often under $2 at Amazon.com) to the cost of downloading a full album in MP3 format. The used CD may actually be cheaper, is more archival (since it won't be gone with a hard drive crash), and contains full CD-quality information that you can subsequently rip to your computer in whatever format you like.
The bottom line is that both CD's and Internet protocols have error detecting schemes built-in. Despite what many people will say about the need to use some specific ripping software or whatever, the reality is that both technologies are very reliable and have a low probability of error. Make your decision based on something else (such as price, flexibility, etc).
Good luck!
Michael
There are some websites, such as magnatune.com, which allow downloading in lossless formats (FLAC), in addition to MP3 files. For these websites, you don't lose anything in data quality by downloading it.
Something else to compare is the price of a used CD (often under $2 at Amazon.com) to the cost of downloading a full album in MP3 format. The used CD may actually be cheaper, is more archival (since it won't be gone with a hard drive crash), and contains full CD-quality information that you can subsequently rip to your computer in whatever format you like.
The bottom line is that both CD's and Internet protocols have error detecting schemes built-in. Despite what many people will say about the need to use some specific ripping software or whatever, the reality is that both technologies are very reliable and have a low probability of error. Make your decision based on something else (such as price, flexibility, etc).
Good luck!
Michael