New memory not seen in 6Y computer, "memory coding" problem?

Gentlemen,

I have added memory (1x64M PC-100stick -> 2x128M PC133 sticks) to a 6 year old computer (eMachines with 2 memory slots, upgraded from Windows 98 to XP Professional), but the computer is only presenting the company logo screen and becomes hung.  There is no response when pressing a capslock or numlock key, control-alt-delete is not effective, and the machine is only taken down by pressing and holding the power button for 7+ seconds.

When I reinstall the original memory, the machine boots fine.  If I install one new stick, the other, or both new sticks, the machine remains equally hung.

I called eMachines and talked with someone in technical sales, about what differences or special qualities that this eMachines computer might require.  Besides offering to sell memory that is assured to work for a substantial sum over what I got, he mentioned two things that were interested: 1) memory coding, and 2) stay away from "new" memory.

I did follow up and ask what he meant by this: "memory coding" relates to identification within the memory that indicates it's size, and new memory tends to be incompatible with old machines.  

My understanding is that, as long as the memory is constructed to a certain standard, is a certain form factor (164 pin SDRAM), and it's performance meets or exceeds a standard speed rating required for the motherboard, that unless you're overclocking things or have,  memory is pretty much memory.

Perhaps I'm missing something subtle yet profound, but I'm loathe to recommend spending $60 per stick X2 of slow, seemingly ancient and archaic memory.  Can anyone add some words of experience when adding memory to an older machine?


Thanks in advance!