It's mostly all been said, but just to add my 2c. Your PSU currently works, which is nice, but I wouldn't recommend using it for any hardware you'd be sad to lose. If you're planning on putting a GTX 960 in there, I wouldn't risk that PSU frying it. I've used lower end PSUs (not off-brand ones, but low end name brand) with decent success. I had a Cooler Master Real Power 450w that managed to drive two 4870s in crossfire for years. It eventually weakened to the point where it couldn't keep them stable, but I was lucky the thing didn't blow up. I've invested in a couple nice quality PSUs for my larger rigs and even if a weaker, lower quality PSU would have worked, it's just comforting knowing my expensive hardware isn't at (as much of a) risk.
My old Athlon XP 2000+ system blew to bits when a decently nice Enermax PSU decided to bite the dust. I wasn't pulling much power at all or anything, it just decided to spark and smoke. Took out everything except my CD drive.
Corsair PSUs are usually well liked, depending on which series. I've heard their lower end offerings aren't all that great, but whichever one you look at, I'd always recommend checking reviews. Budget PSUs are okay for budget builds, but if you start drawing higher amounts of power, I would suggest going for a nice PSU that's going to give clean, stable, reliable power.