This is not a yes or no thing; it's much more complicated than that. Simply do to how is up and over sampling done by the particular model, most major brands have there own way of doing this and therefore it is not possible to compare them as one.
Over sampling is as mentioned before in the thread just reading the same bit a number of times and then the logic decides if it is a "0" or "1", usually it will just be the number that gets most "hits" - no guarantee that it is the right guess.
Up sampling is much more complex and more likely to be wrong, since as cracker says it has to put information into the signal that is not there. Often quality is wrongly mistaken as a more comfortable sound. Most people can sense the sharp edges on the wav curve coming from an old CD-P (at least when comparing to a good quality vinyl cut of the same tune) but when they hear the CD on a new up sampling CD-P it is much more soft and nice for the ear. This is not quality but just making the wav curve smoother, there is no guarantee that the added information in the wav curve actually truly represents what was played in the studio - it is purely a result of the logic in the DAC. This is a fact and can not be discussed, the discussion can only be how close to the studio is the signal - is it close enough?
In the other end there is the no nonsense makers who says; do the job right from the beginning, don't use logic to save you're a.. Make a high quality transport that actually reads what is on the disk, and then there is no need for over sampling! Make a high quality DAC and analogue stage - then there is no need for up sampling.
In the Pro world the rule of thumb is simple; never convert or up sample if in any way possible. When sample rate is changed it is always downwards and in even numbers, if the recording is aimed for CD the recording is usually done in 88.2 kHz (2x44.1). Try do the math going from 96 and down to 44.1, bummer - remember there is no "after the comma". Now try to imagine going the other way from 44.1 and up to 96, you see how the problems just start piling up
This is not to speak for or against CD-P converting, but only to give an idea about what it's all about. In the end it will come down to the good old "In what do you believe, what is you're religion".