Heat sink temp to the touch

Is is ok to touch you heatsink with the PC running to test to see if it is warm/hot (grounded of course)...?

I just installed my slk-900u and i am getting idle temps of around 42-43 with a 2200mhz OC on my barton 2500+ with an enermax 92mm fan (fullspeed)....
I am concerned that i'm not getting enough heat transfer since i was hoping to pull <40 at least...

How hot should the HS be to the touch? burning? warm?

It will just be warm. Actually, not even warm since your skin is 37C and the heat sink should be cooler than that with the processor being 42C. You probably need a side case fan or duct to get it a little cooler if you don't already have one.

That's another question - I have the fan blowing down but two case fans near it blowing air out....

should i reverse the case fans at all?

Depends on how many fans you have and where they are located. In general, the side fan should be going toward the CPU and the rear case fan should be blowing out of the case.