What about the hardware test CD that comes with your computer? You can either do short or long tests (and loop them) and I've found it's pretty good at finding if there are ANY hardware issues (RAM included) on your Mac.
I would use the Hardware test CD from Apple first. Otherwise, I know TechTool Pro 4 will run various tests on RAM. I'm not sure about what Norton and DiskWarrior do.
you could always put the memory in an x86 laptop and run memtest. however, since the program is gpl, you may be able to port the program over to the mac.