Are these temps ok?

Yes, those temperatures are reasonable. With a 2500K, your "worry" threshold is around 74-80 degrees C, and you're not near there. The one thing I'd recommend changing is your voltage (I'm at 4.5 GHz with my 2500k and 1.35V), though this won't affect temperatures much.

My own temperatures hover somewhere around 58 degrees C, but only because I have a high-end Corsair water cooling system.

Just remember, you'll almost literally NEVER encounter such temperatures when you're using your PC for ordinary work. Prime95 is designed to push the cores to their absolute limit. So 68C is as hot as you'll pretty much EVER get.

A helpful tip: I'd recommend ramping down your over clock a bit for daily usage. 4.5GHz is a large step up from the intended 3.3GHz frequency, and will undoubtably limit the lifespan of your CPU by a bit. I keep my 2500k at around 4 GHz for everyday computing.

Hope I helped!

Have to agree. 4.5 on air is very aggressive for full time use although I don't think you're in any real danger with those temps. If you are running some kind of 24/7 application like SETI@home or some other distributed computing on all cores, I would then say for sure lower your clocks but for everyday general computing needs, your temps won't ever get close to those generated by Prime.

I was under the impression that a voltage of 1.26 was really good for 4.5GHz. But I'm running that speed for gaming so it doesn't bottleneck my GTX 680. Does that make a difference or what speed would I be good at?

Higher clock speeds can make your system unstable but wont damage your CPU, excessive temperature and voltage will.
When the die temperature gets near or close to 80degC then the lifespan of the IC will start to deteriorate exponentially.
The temperature of the CPU depends on many factors: power dissipated by CPU, thermal conductance of the die and CPU
casing, thermal conductance of the junction between CPU case and heat-sink, the thermal conductance of the heat-sink itself
and the ambient temperature of the PC casing (that depends on the ventilation capability of the case and the ambient
temperature of the room). Improving any of these stages should help to reduce core temperatures.
If the room temperature is high then it scales up to increased core temperatures as well. If you cant open a window or
turn on air conditioning, then easiest solution is to bring down the power consumption of the CPU. Maybe your CPU
can also handle lower voltage?
It is easy to find out the optimum CPU speed by monitoring and comparing the frame-rates of some games that you
like to play with your current 4.5GHz and with a lower settings, if it starts to bring down the frame-rate near to 60fps
then you have reached the limit and go up a bit. This is highly dependent on the game but in general should help to
reduce the temperatures a lot.

Regards
Marek

Thanks a lot for your input Marek. I've lowered my overclock to 4.2GHz without any noticeable performance decrease in games. I've got my voltage set at 1.200 in BIOS and my system is 14 hour prime stable (blend). I also put on new TIM (antec formula 7) . Running prime small FFTs @ 77F room temperature my CPU temps max at 50, 55, 57, 56. Nice improvement in my temps. However, one thing has me puzzled. As I said before I have my CPU voltage set to 1.200 in BIOS but I'm getting different readings in windows. CPU-Z reports 1.160 at full load, HW Monitor is saying the same but with 1.19 under max, and core temp is saying 1.3771. I'm not sure which is accurate so could someone please explain this to me? Thanks!

Core temp reads off the VID, which is the suggested amount of Vcore for that clock. Disregard, instead use readings directly from bio's or cpu-z.