Truly, I built three machines for work that incorporated 256 megs of the High Performance Rev.2 Mushkin pc133 ram + T-bird 800's and Asus A7V's.
I was not impressed with these sticks. Two of the ram modules wouldn't work, period. They RMA'd them and the replacements were their value ram (read: generic chips they slap together on a pcb). Needless to say I was peeved. After calling them back they claimed that it was their policy to only RMA an order ONCE so I was basically stuck with the lower performing ram modules as replacements for the Rev.2 ones.
Well, I told them to F*** off and threw those junky modules into a couple of secretaries' new machines and bought Crucial Cas2, which has had absolutely ZERO (0) problems, even when oc'd to 148mhz for fun Since then I've built around 50 AMD T-bird and Duron machines and used Crucial for all of them, without a SINGLE problem.
Anyway, I've dealt with Mushkin prior to this as well, and had decent service, nothing special. In fact, they remind me of the mouse company Razer. They certainly seem knowledgeable about their niche market, but they truly seem like n00bies when it comes to retail sales and service. Anyone who's ever dealt with both companies for sales and product returns will know EXACTLY what I'm talking about.
I'd say at this point, for compatibility's sake, never go with anything other than the Crucial 256meg parts. I've not ONCE heard of any issues with them, except in extreme overclocking situations (where ram can't easily be determined to be the instability culprit, anyway), and at their current prices, why would you choose anything else?