currently got 133 sdram in my pc. can I 'convert' my pc to run on ddr or will it require a new compatible motherboard.

it's a 2 yr old P4 1.5ghz if that's relevant.

 

In short, no, you can't. If you want to run DDR then you need a replacement motherboard.

 

depends on board model some boards have dual support, meaning you cant run them together but it can run on either, would need to know mobo model to be sure, do you know what it is? and i can tell you

 

IIRC the SDR/DDR hybrid boards were all Athlon motherboards, weren't they?

 

I think ASRock (Asus budget brand) did a VIA based P4 board that had SDR/DDR slots. Will be long in the tooth by now though, so I'd save your money and maybe wait for the impending new socket size from Intel (which has two new chipsets)