Right memory for a dell dimension L___R

Hi, I have some friends with the following boxes, and they want to upgrade the memory, I think, if I'm reading the tech specs right, that any of these boxes can use PC100.

The boxes are Dell Dimension models L500R, L667R, and L100R, and these tech specs seem to cover all 3 boxes. It indicates that for all 3 systems the memory speed is 100 Mhz - aka pc100, right?

The thing that confuses me, is that in the microprocessor section, it says that some of the chips run at 133 Mhz externally. I should disregard this because in the memory section, it says 100 Mhz, true?

Anyway, thanks for helping me sort this out.
Jim

 

PC 100 looks about right to me.

Note that the maximum memory they can have in their systems is 512 mb.