I can't speak for infineon, but I have a 256 stick of Micron CAS3 PC133, with a p3800EB @ 900 on a CUSL2. The ram is running at 150, no problems yet, no crashes at all since I built it the first week of November.
That brings another question to mind, could my RAM be frying as we speak? I was kind of under the assumption that @ 150, either it will not post at all, or it will work fine for a long time. Could the fact that I'm clocking it that high cause the RAM to fry over a little while, say, 6 months or a year?