I had a quick look at your motherboard manual and also the Asus forum for your board for you.
at first glance it looks very limiting what you can adjust in the bios to up the speed of your chip. However, some seem to be able to on the asus forum but it may require a bios update. you can find out how to do this in your manual.
Others have mentioned a "top performance" mode that you can select in your bios - this may be an option for you other than selecting load default values. Difference between the two would be default is a fail safe mode which should boot without any problems and top performance will set everything to the max rated values/speeds for you automatically. however, if there is a compatibilty issue with a component it may not boot/post which will require going back into the bios and resetting back to default or if you cannot clearing the cmos once again.
http://vip.asus.com/forum/view.aspx?id=20070701234646687&board_id=1&model=P5VD2-VM&page=1&SLanguage=en-us
The things above would be te first steps to try. look to see you if you have this top performance mode first, if not then look into updating the bios. remember to follow the instructions exactly in updating bios. Best option for you would be to use Asus' update programme in XP/vista because it will check the bios flash is compatible first.
Also noticed there isn't an option to change the voltage of the vcore (CPU voltage) this will limt overclocking. Not a bad thing if you are unsure what you are doing as there is less chance of you causing harm to your system!
seems like the only real way to go if you want to OC your system is to BSEL mod your CPU. I am not brave enough to do this myself, yet, but also have not had reason to. basically it involveds taking out your CPU and shorting a couple of pins with a silver contact pen. What this does is make the CPU tell the motherboard that it is runs at a different speed i.e. 1066fsb instead of 800fsb. the advantage of this is that there is not need to go into the bios to change anything (or if you cannot at all) and also because the cpu tells the motherboard it has a new/higher stock speed everything else runs at stock i.e. everything else runs at normal speeds - your motherboard just thinks it has a faster cpu installed. this doesn't mean doing this your system will be running stable at a higher speed. other things to consider is additional heat prodcution becasue its running faster and also becasue it is running faster it may require extra voltage to run it stable. but again extra volatge will mean extra heat! apparently you can revert to how it was before by cleaning off the pen.
Have a look at these links first is someone with same board and cpu as yours. second is all about BSEL and VID (voltage) modding:
http://vip.asus.com/forum/view.aspx?id=20070630183237859&board_id=1&model=P5VD2-VM&page=1&SLanguage=en-us
http://www.overclock.net/intel-cpus/341123-intel-bsel-vid-mod-guide.html
Have a good read and decide if this is the way to go. if you do, only do the 1066 bsel mod - your board won't support an fsb of 1333. try it and stress test it. if its not stable and the temps are not too high then look into a VID mod to up the CPU's stock voltage too.
Good luck & good reading. Perhaps the more experienced members here can expand more on this subject for you and provide some more info on the possible risks???