One the last three builds I've seen great results running 2gb of Kingston memory on each. The only time a problem was seen was due to the board on one older build reporting errors on both Kingston and Corsair.
The next build saw 0% errors on both sets of dimms by both brands! That old board also refused to support the correct fsb for the cpu since it just loved batteries for some reason. Both are quality brands just like OCZ too while Corsair has more of a gaming rep for the xms series.