Could someone explain to me in a nutshell how 10mb and 100mb co-exist happily on the same ethernet? For example, I have 3PCs and a DSL modem on my local network. 1 PC and the modem have 10mb cards and 2 of the PCs have 100mb cards. When I transfer a file from one of the 100mb machines it takes about 5 times less time than when I transfer to the 10mb machine, so it certainly appears that the network is capable of both speeds. Evidently the 10mb is able to detect and handle collisions with the 100mb and vice versa. Perhaps it's because they both use the same carrier frequency; if they use such a thing? Also, is a 5x speed difference what I should expect? Not 10x? Take pity on me. I'm a software guy. Mike