Gigantic disappointment in gigabit

I bought a cheap 35€ gigabit switch on saturday and some more cat-6 cables, in an attempt to get my home network upgraded to gigabit speeds. It failed.

I found out that my new "gigabit" 500GB Buffalo LinkStation was not able to provide more than one tenth of the gigabit, about 10MB/s with Samba from Linux. With FTP, I was able to get enormous 15MB/s. With Windows XP, the access may have been a bit faster, though I did not measure that more accurately, because Windows doesn't report transfer speed when copying files. Between two Linux PCs, I got a maximum of 35MB/s with scp. Curiously, with KDE file transfer over sftp connections, I got only about 10MB/s.

It appears that I was a bit too blind expecting that gigabit upgrade would be as painless as 10Mbps and 100Mbps upgrades were years back. Apparently, the current PC hardware simply can't deliver gigabit. The integrated "gigabit" network cards apparently use PCI bus, which has theoretical maximum of one gigabit (32 bits * 33 MHz). But that's only in one direction, while gigabit ethernet is usually Full Duplex, so it would require two gigabits of bus.