Oh, I knew that, I was talking about real throughput. E.g. at the same distance from the access point, while I can see an mpeg2 stream (between 5 and 7 Mbps) with my laptop (with any of the adapters mentioned above), with the tablet I cannot even see a downconverted stream at around 1Mbps.
While that could be due to other factors (maybe the wifi adapter sucks too much cpu, maybe they keep the driver secret to try to conceal other defects), the fact that I can associate more easily with those adapters than with the tablet indicates that the much touted n800 wifi performance isn't that spectacular.
Either that or I have been particularly lucky choosing the cheapest adapters I could find that outperform the tablet.