tethering a camera?

[BabaG]

i doubt xnview does this but maybe someone could point me to something that will.
can xnview be used to control any cameras for capturing to a laptop? if not, what
can anyone recommend that i could use to capture frames from a panasonic lumix
g2, olympus e-pl1, or sony nex-3 to a folder on my laptop?

thanks,
BabaG