Keep in mind that the 360 gets a boost in overall total sales due to its unreliability. Many people have bought one 2 or 3 times already.
I didn't want to include that information, as, to my knowledge, there is no reliable way to know how many users of both PS3s and 360s got a replacement console through the warranty, how many simply bought a new console, and how many opted not to replace a broken console. However, if you wanted to do the accounting in that manner, you might multiply the number of sales by the failure rate of each console, for a back-of-the-envelope calculation of the number of faulty consoles.
I'll use the figures quoted by Famine in
this thread, since I cannot seem to find a good source on this data (if anyone can point me to a reputable source to either confirm or correct this data, I'd appreciate it). The figures he mentioned were a roughly 3% overall failure rate for the PS3, and a roughly 16% failure rate for the 360, so the number of broken consoles to date would be around 0.7 million PS3s and just over five million 360s.* Taking this into account, the gap between the number of 360s and PS3s that have not failed to date would be roughly four million.**
* Remember that this is a back-of-the-envelope calculation, and should only be taken as a very rough estimate.
** Since this is based on estimated values, this figure should also be taken with a grain of salt. Additionally, since there is no way to know how many owners of failed consoles got a replacement through warranty, off the shelf, or not at all, the meaning of this figure is up for interpretation.