Hi, I used this PSU calculator here http://www.thermaltake.outervision.com/Power
and made a couple of assumptions - that all your hdds would be in, that all your USB ports could be in use and that you have 2 x 120mm case fans - one in one out.
I made your recommended wattage psu, at 90% load for max efficiency, 341 watts. So yes, you are way over what your PSU can take. Also, since the P4, you will need additional power connection to the Mobo - a big plug and potentially a small one, check your new mobo manual as the CPU power can sometimes be on another plug - if so, I doubt your old unit has it due to its age.
If I were you, I'd get yourself a 350w or 400w psu, and try and stretch to a badged unit if you can, the no-name units are cheap yes, but rarely deliver what they say on the tin and in tests here on THG have at times literally blown up when loaded to the levels they say on the tin.
Bear in mind also, that PSU makes no allowance for later putting in discrete graphics if you decide to upgrade them - so if in future you put a card in, you would need to also put in a 450w+ psu as well depending on the card.
Hope that helps some.