DDR2 vs DDR3

[mtjdavis]

I'm looking into buying a new rig and i was wondering..

Is there any realistic improvement with DDR3 instead of going with DDR2 ?
Or should i say is the extra cost worth it ?

Also is it worth going DDR3 to be fairly safe for the future or is DDR2 going to be around for some time still?

Thanks in advance.