PSU: I've been running two Kingwin units almost non-stop for two years now, been moved from system to system countless times and I've never had a single glitch. One was even dismantled, painted and reassembled twice, and had the 8-pin connection cut off and then reconnected. It's been abused, really, and hasn't complained at all.
RAM: I've never had RAM fail. I've used OCZ, GSkill and Corsair
Motherboard: MSI. I have three of them in use at the moment, and again have never had any issues with any of them. Only once have I strayed from MSI and that was for a high-dollar Asus board that failed.
Hard Drives: Samsung. I've lost Hitachi and WD drives but never had a problem with Samsung.