Cable Modem Recommend

Hi,
My mother in law is getting Cox internet and I was wondering if anybody
had cable modem recommendations.
She has a Mac using OSX if this matters. Do you have to use a USB serial
connection to set things up or will it just work by hooking it up?

I have DSL so I'm really not up on this subject. I saw some modems at
Comp USA for 59.00 and 79.00 but didn't see much difference other than
brand.

Thanks,
Eric