With a Core i3 530 I would expect temps around 50C. I can get 50C on my overclocked Athlon 64 x2, and that's a 65nm 3.2GHz part.
I would definitely consider an aftermarket cooler, maybe even one that comes with a backplate (for a more secure fit). It appears that Geminii S comes with backplates/bolts that secure the heatsink all the way through the board (unlike those flawed screw-ins). Just make sure you get one with fans installed, it looks like the Geminii S allows for 1x120mm or 2x90mm or 2x80mm. I'd go 1x120mm, its quieter.