My new iMac only has TORX screws on the back--apparently some fluke at the factory since no one else seems to have heard of this. My sales rep at the place I ordered from suggested I purchase a set of screwdrivers, which I did for $9.95 at my local hardware. The problem of removing the memory card panel is now solved, but guess what? The additional 1G memory I purchased is not the right kind . . . and upon looking it up again at the seller's website, I see that I have apparently been overcharged for this item by $26.00! Of course, now I have contacted them for the second time today. In case you're wondering, it's MacMall. We've had little problems with them in the past, so I'm not too surprised, just a little exasperated with the situation and wondering if ordering direct from Apple.com would have been smarter. Thanks for all the responses I got to this question.
PowerPC G3 Blue & White Mac OS X (10.1.x)