Glad you found the problem, Matt. The memory you linked to is listed as
144-pin SODIMM for the iMac. The beige G3 takes
168-pin DIMM.
I usually buy my memory from either
OWC or
TransIntl , but Crucial has a very good reputation and I would buy from them, too.
The beige G3s came with PC66 memory, but I'm using PC100 and PC133 in mine. Make sure you get 2-2-2 or CL2 speed code. And in case you hadn't heard, it will take up to three 256 MB sticks, but not the 512 MB ones.