I wouldnt the pentium D series isnt a cpu i would want to overclock i still own a Pent D 925, even tho i shout @ people for calling the Pent D cpu's as in the most case these people are sheep who have never owned a Pent D and are baseing there opinions on what others say. I would not recomend OC'ing it they are quite capable cpu's and run fine @ stock speed's some maybe a little hot. They tend to have a bad reputation for overheating so OC'ing it would prob cook it. My Pent D @ retirment could run oblivion/COH @ more than playable levels i intend to use it again for my stepdaughter.
You can overclock safely as long as your temperatures and voltages are with in technical specifications. In most cases, even the the older p4's can handle light to moderate overclocks, provided decent cooling and case air flow is present.
I suggest doing some reading on how to overclock the Pentium D and go from there.