New Mobo/Processor? Way too many variables changing there to say whether your choice of DIMMS are going to make the difference.
Understand, though, that the purpose for 'fast' RAM is to allow headroom for processor (FSB/BCLK) overclocking, rather than any performance increase in and of itself. On the front page there are a couple tests on the effects of memory running at different speeds. The corollary to that rule is that you want to be sure you have a little bit more RAM than necessary to ensure you have room for your apps and a little cache~ing. So, something to think about is 'downgrading' your memory to a slower speed in order to have more of it.
Some articles on memory scaling and performance to read:
Sorry I was to vague
I am going from a crappy HP Motherboard And a E2180 2.0GHZ 3GB 800MHZ DDR2
To Gigabyte GAH55M-S2H and i3 530 With 2GB 1333MHZ DDR3
I should have asked if 2GB DDR3 is enough RAM for what said I wanted to do Above ?
Simple: Keep an eye on your memory usage, and pay attention to peak values. Once you know that peak value, then you know whether you have enough or not.
i.e. As long as your peak values are 2GB or less, then your intended configuration is adequate.
If you currently use more than 2GB, then what will happen is your system will need to page data to/from the hard drive, in order to run everything. This is several magnitudes slower than if you had enough RAM. And therefore there will be a performance impact.