If ALL you need it for is to alert cars of your presence, it's probably minimally OK. That taillight looks uber-weak to me though. Personally I'd go for a Planet Bike SuperFlash/Blaze combo if you can swing it. I still wouldn't trust them in really bad weather, but that combo would be OK by me in clear weather.

One thing I've learned over the years is that cheap bike lights is expensive - either they break and you have to buy another light, or they turn out to just suck and you wind up buying a better light anyway. I have spent far more money on cheap lights that sucked than on my current setup that's really good.