Add wireless card to CPx

I have a CPx notebook that's running W98 and I want to add a Linksys wireless modem card in order to use my new cable access with it.  According to Linksys, I need to have W98 SE in order for it to work.  Being that this laptop came from work and I don't have the original product key, do I need a Full Version of 98 SE or can I still use just an upgrade even w/o having the original product key?