What can I expect from the switch from SDRAM to DDR?

[hardwareguy1241]

I am currently running an Athlon 1gig OC to 1.4gig on a KT 133a based motherboard. (Ga-7ZXR rev2.2)
How much faster will my PC be if I get a KT 333 based mobo and some PC 2700 ram?
Im thinking around 25%, but I need some more input.

Summer is upgrading and computer selling season for me.
(No school, you know )