From another site: 

"if you have ridden it down this far, this would be the absolute *worst* possible time to get out. If we have not already seen the bottom, I think we are very close, and for a Long, minimizing the risk of missing a substantial upside move simply to avoid a little more pain on the downside should be paramount".

I personally have sold some poor performers and kept better stocks like MSFT, GE, PG, HAL, CSCO.  I will stick with these awhile. 

Bad

The results of the entire bull market of 2003-2007 are now all but obliterated

Probabilities

Interesting article on the mathematics of investing.

http://www.slate.com/id/2201428/