Need affordable prime lens

Thanks. From what I've heard, RainbowImaging adapters should be quite good.

No, it's not. But I wonder if those two are good choice for what I wand (primarily indoor taking picture of my baby)? Both Canon and Minolta has 50mm f/1.8 lens which I can afford. Is one of those two significantly better than another and why? Is there any other option I should look for? And... is that what I need? Will pictures taken by any of those two (or some other lens you can recommend ) really be better in low light situations than ones taken with kit lens (16-50)? Or my purchase is just pointless waste of money.