Yes, I know the difference between megabits and megabytes and therefore I write: Mbps for megabits per second and MB/s for megabytes per second (I could write MBps for the latter but it is easy to make a mistake then).

My network speed is 100 Mbps = about 12,5 MB/s (1 byte = 8 bits)


Common Name: 100Mbps
Used With: Fast Ethernet
Time to Transfer 1 Megabyte: 1 Sec

Didn't you mean 10 Mbps? When you divide 100 000 000 by eight shouldn't you get 12 500 000 which is about 12,5 MB/s?
(I can't remember now if Mbit stands for 1 000 0000 bits and mbit for 1024 * 1024 bits or on the contrary, but it doesn't matter here. It is still much more than 1 MB/s. Also I don't know if this notation is used now... it's generally better to use Mibps for 1024 * 1024 bits. Look here for more info: http://physics.nist.gov/cuu/Units/binary.html).

Secondly... if this transfer is normal in 100 Mbit network, why are other computers reaching five times higher transfer rates?