BEST OC MOBO FOR Q6600?..how high hav you o/c yours HELP

hi, i am getting a q6600, and want to overlock it to about 3-3.5ghz..i can do that BUT

What motherboard would be best???
so far my options are ( and there in my price range )
GIGABYTE ga-p35-DS3P
GIGABYTE gs-p35-DS4
Asus P5k
ASUS P5Ke wifi


what is most reliable/futureproof..and easyest to overclock q6600 as high as possible

( i do have watercooling )
the only specs i am really fussed about
1333 fsb
Crossfire if possible
pci x16


specs
alive-xfire Esata2 mobo
Amd athlon 5200x2 o/c
4gb ocz
200gb x2 sata