SME5.6 has the driver built in for the Intel 1000MT card, it just doesn't autodetect it. There's a thread on the forums that discusses how to manually set SME up for this card without installing a new driver.
SME6.0b3 fixes this. It is autodetected without any issues.
I have used Dell server's with the NIC built in...
PE2600 and PE400SC are two examples.
Addon Intel NICS work as well.