Iam running Neo Hd on a Minimum Spec Machine as outlined on the cineform web site,
its a 2.66 mhz dual core
4gb ddr3 ram
win 7 64bit ultimate
with a 250 gb sata 2 video drive.
Intensity pro card.

when i have hd link up and running, i have the windows task manager up and running so i can see the cpu usage while iam capturing.

with the live display off the cp usage is as follows

medium quality cpu usage 65%
high quality 75% to 85%
filmscan 1 85% to 93%
filmscan 2 87%to 95% sometimes hitting 100% for a few seconds.

My question is if iam using film scan 2 for blue screen work, iam i dropping frames if the cpu hits 100%
the tests i have done so far. Looking back at the footage, it dont look like i have dropped frames.

Secondly if i turn on the live preview on hd link iam i pushing the cpu to work harder?
iam i more likely to drop frames because of it?

There is a chance you will drop frames if the CPU sustains at 100% for too long. The frame buffers do allow for some 100% saturation, but would avoid any mode that is regularly over 95%. Filmscan 1 will be sufficient for a nice key. The preview does add more CPU, put will favor the encode and it will drop preview drops so that the encoder doesn't drop any.

Can you overclock the CPU or RAM speed? That will bring you above the minimum specs.

I dont think the motherboard allows for even a mild over clock on the cpu but i can try with the ram.
So David if i can upgrade to the 2.8 core duo, i should be ok to run on all the quality settings without a hitch?

2.8 alone might not be enough. Memory speed is a bigger performance gain.