Different people have different opinions about what drives they like and what kind of reliability they have, but the reality is probably that every manufacturer makes a dud once in a while (perhaps like the one in your Mac mini, unless it sustained a drop or some other injury). At least with two copies, you'll be reasonably protected. If it's really critical, consider a third stored off-site (e.g., your office, you parents', etc.)
I use a WD MyBook Essential 350 GB, and it's been working flawlessly for a few years now. I do have to confess that I've heard a few more stories than usual about LaCie Rugged drives dying early (click of death, silent death, and others), but again, you'll bound to hear at least a few such stories with any manufacturer, so I wouldn't necessarily let that discourage you.
I guess the bottom line is to find something you feel comfortable buying, both in terms of price, storage, and what kind of warranty is provided. You can also check out user reviews (Newegg, Amazon, or wherever), but I have a feeling that people tend to be vocal only when there's a problem, so one person complaining doesn't mean they're all bad. However, they might at least alert you about other things you might want to know (e.g., doesn't require external AC adapter, included USB cord is way too short, etc.).
