According to Nvidia
the 9800GTX+ has a TDP of 141w, so even if you consider a generous overclock that would get each card to use up to 170w, you're at 340w.
Then the i5-2400 has a 95w TDP, but that is including the GPU, so you're looking at a CPU that will use around between 65w-75w.
The SSD will use very few watts and the HDD will use less than 10w while working.
The DVD drive will use up to 10w while being used, at idle it will just sip power.
LEDs are fairly power efficient, so you shouldn't worry about that.
All in all you will be using less than 500w with that setup, so, yes the CX600 will be able to handle it.
I would only advise you against the cards themselves if the price is too high. Don't forget that they are only DX 10 and SLI may or may not work with newer titles and to different levels of scaling.
Depending on the price, if it costs nearly the same, the same or more than the new GTX 650 ti, then you're better off buying the GTX 650 ti until you buy the GTX 680s. It will also be a card that will hold its value much better than the 9800GTX+s and that you can use much more effectively in a secondary rig.
Here is a comparison on Anandtech's bench
between a GTX 285 (they didn't have anything more appropriate to compare to) and the GTX 650 ti.
Edit: here is a comparison on Tom's Hardware Gaming Graphics Cards Charts 2009 (High Quality)
between a GTX 285 and two 9800 GTX+ in SLI. The superclocked version should be able to get a bit higher scores, but the as you can see sometimes the GTX 285 wins, sometimes it loses. But take into consideration that that is a chart from 2009 and newer games may not give the same overall result. I just wanted to give the most complete information. Now you can take the difference between the GTX 285 and two 9800GTX+ in SLI and compare it to a GTX 650 ti. If the price is similar, getting a new card, with a warranty, with higher performance, with DX 11 functionality and lower power consumption is a better deal. But it will depend on the price, of course.Edited by tpi2007 - 10/11/12 at 5:28pm