Thrax: If that one error shows up more than once, yes, it's almost certainly an indicator of a failing stick of RAM. But if it shows up in one run of the test but isn't seen in subsequent runs, it doesn't necessarily mean anything.

On a side note, a whole bunch of errors in Memtest doesn't necessarily indicate bad RAM. It could also be a failing motherboard. I had a friend with an Abit KX7 that was crashing all the time. Ran Memtest. Got hundreds of thousands of errors. But I took the RAM home anyhow, and threw it in my MSI Pro266TD (dual P3, DDR). Ran Memtest overnight. Zero errors. He's now using that same RAM in an A7N8X, and it's working fine.