do burned or ripped cds from a computer sound as good as new cds bought from a store? the reason i ask because i have some burned cds in my collection and i'm not sure if their sound quality would be the same as the orignal cds. what do you guys think?

It depends upon the format that the CDs were ripped to. IMO if a CD is ripped to mp3 then burned back to audio CD there will be a noticable reduction in sound quality from the original cd. If you use one of the lossless compression formats (e.g. FLAC) to burn a cd it will be identical to the original and so there is no reduction in the quality of the audio.

If they are simply burned copies of commercial discs (meaning the data's never been through conversions such as AvFan mentions), then there shouldn't be a difference. I have read some comments that have suggested that multiple repeated copies (a copy of a copy of a copy of...) could introduce errors in the data that add up to some sonic differences, but I'd expect that to take a significant number of generations to yield an actual impact in sound quality.