if both desktop and laptop have network card,
you can connect them with one cross cable (different from the one you use to connect desktop/laptop to network socket)
then configure the two computer's ip to be in same sub-network, say
192.168.1.100 and
192.168.1.101
then you can do ftp or network sharing within the two.
USB data transfer suite is available in market, around S$50(??)
it connect two pc with USB cable, and need to install software driver.
for serial port cable i never tried, but it should be working in some way.