A straight burn should produce little or no loss. There is the possibility of error with skipped data caused by the burning equipment and the equability of the recording equipment or screen saver kicking in while you are recording. Since no compression is involved the results should be the closest to the original that can expected when not using professional equipment.
Naturally I avoid using the computer when burning. To get the best possible result. I know most software these days say you can keep working, you can wind up with little skips that are distracting, cause by resources being too low for just a moment. Not detrimental to the overall recording but sometimes enough to be annoying. Even to burn Photos to disk I turn off screen saver, any programs that run timed checks, MSN and Internet browsers (emails and explorers). In the end the only thing running is the burn program. Set to burn and go to make myself a cup of coffee. I also do my burns after a start up to ensure resources are available, closing programs does not return all the resources for a while. It just burns faster and better after a fresh start up 
Alex
