Monitor scaling?

[Nda]

I recently just purchased 2405 FPW and using my 6800 gt oc from BFG, i am wondering, which one should i choose in the setting for monitor:
a). display adapter scaling
b). centered output
c). monitor scaling or
d). fixed aspect ratio scaling

which one is the best one to use? currently i chose c (monitor scalign), desktop is at 1920x1200, i play games alot, coh and farcry run at 1920x1200, but halo run at 1600x1200.
Thanks in advance.

 

[Reiniku]

When playing halo you'd set it to b so it centers on the screen, and I don't think it matters for while playing at native res.