airport card for older imac

Hi there all. I'm new here and , honestly new to macs. I purchased a nice 500 mhz imac on ebay for my five year old and I have read that it is capable of having an airport card. I can't get any info out of the mac experts at apple but I just want to know if there is any special airport card I will need. Will this take the newer g or n type of card or will it handle just the 11mbps cards? I know I will need an adapter for this. I have access to all of this but want to make sure it will work for my daughters mac. This is a summer 2001 edition. Also, I have a linksys wireless g router. Do I need an apple router or would the linksys work fine? Thanks for any help.