I don't think it's Trainz. Hard drive longevity is determined by a number of factors but one of the key ones is heating and cooling cycles (think: How often you turn your comp on or off, or if you have some really weird airflow issues at work.) It's thought that repeated heating and cooling cycles break the microfine wires in chips and elsewhere, much as bending a spoon back and forth will eventually break it.
Also, if you're a system builder, I'd avoid OEM HDDs and buy retail boxed (actually, this applies to ALL parts.) I've run into too many dodgy OEM products, which, I suspect, are returns, factory-seconds, etc.