ddrram

I have a 3+ years old P4 1.7 GHz machine with 256 mb SDRAM (133MHz). My motherboard supports both SDRAM & DDRRAM. I was thinking of upgrading my ram, by adding another 256 mb stick to total 512 mb. (also because thinking of buying a dvd writer soon). now my question is - which is better...

Well i have been facing it from last week only n the prob z very new. The power is there on the green light of motherboard as well as the outer LED of the cabinet. As soon as i switch on my PC cabinet's LED gets ON. But nothing comes on monitor (I mean booting actually doesnt start). Config...

AMD FX-51 ( 2.4GHz Socket 939 / 940 ) motherboard K8T Master1 (MS-9130) Gigabyte GA-K8NNXP :? asus_SK8N asus_SK8V Graphics card AGP 3.0 ( 256 MB ) 8x 512 x 2 PC3200 DDRRAM ( which brand ) Cabine

which is best rdram or ddrram? which is faster & suits bests for gaming ? why most people prefer ddrram?