My walmart hp5125 is very happy with the two sticks of this 128MB PC100 non ecc CL2 SODIMM Kingston Valueram I received two days ago. The hp5125 shipped with 64MB PC100 installed, and can be upgraded to a max of 256MB if you pull the 64 and put in two 128s.
What I don't understand is why Dell is selling this stuff for $8 less than the CL3. Based on my limited knowledge, CL3 can potentially slow your system because it requires 3 clock cycles to respond versus 2 clock cycles for the CL2. Clock cycles, of course, are so infinitesimal in duration that you'd be hard pressed to tell the difference in most applications, I suppose.
FWIW, I spent $48.95 each for mine, so I sent email to Dell indicating that "a friend" had gotten a refund of the difference, and requesting that they please do the same for me. I'll update this post if anything positive comes of it.