Measure twice, cut once. I spoke with the craigslist poster about the AirPort wireless router for my iMac. He suggested that my iMac probably uses the AirPort Extreme. I drove home yesterday instead of over to his house and double checked my computer. Yep, iMac G5's use AirPort Extreme. I saved myself the trouble and the gas of going into two separate rush-hour traffic routes. Here's a big thank you to this fella for knowing his stuff, and a big sigh on my part that I recognize it is always worth looking one more time before making a leap.
Funny, I'm happy for all the things I didn't do. I didn't do the extra driving. I didn't spend $30 for something that isn't going to work. I didn't open the back of my computer before it's necessary. I didn't try to replace something that might not have even fit, never mind not work. I'm not shuffling this card around on desks then tables and into closets in my house (where it would stay busy collecting dust and weighing down my house).
I am still without internet service at home. I did find an additional window/diagnostics area that let me know my computer is "reading" my wireless card. If I could just get in touch with the apartment manager and have him "reset" just to be sure it is not at that end. In essence I would like to measure three times. It costs nothing to measure.