is this system good for after effect to run all plug-in also?

I agree with Bill. The current version of After Effects is not well multithreaded; it cannot take anywhere close to full advantage of more than four physical CPU cores.

In addition, the X5650 is very old technology, and its lesser-threaded performance isn't in the same league with any of the newer Intel CPUs (even otherwise-lousy dual-core CPUs), and its Turbo speed with more than two cores in use is a lousy 2.93 GHz.

And the Quadro 600 is almost exactly the same GPU as the GeForce GT 430 - a lousy GPU even in its day (2010), and a complete joke today.

As a result, you might as well use a laptop with a dual-core low-power CPU and only integrated Intel HD Graphics for AE if you're going to buy that system for that purpose.

Now, if you're going to use Premiere Pro, sure, the two 6-core Westmere Xeons will beat any current single-quad-core-CPU-based PC for rendering - but then, the really crummy Quadro 600 will hold back the CPU performance way, way back. Almost down to entry-level dual-core desktop CPU level of rendering performance.

I think that is a lousy starting point for AE where the number of cores is not a good choice because AE is not multithreaded. 

look at this testing that Puget Systems has done for us.  If you analyze those performance numbers you will see clock speed/turbo speed is the most important factor. so the 6-core i7-8700K is much faster than that lousy 6-core (x2) Xeon

• Processor Base Frequency 2.66 GHz
• Max Turbo Frequency 3.06 GHz

That Xeon model is discontinued

• Status Discontinued
• Launch Date Q1'10

I would never consider Quadro 600 for any application as it is an antique with that DDR3  memory and also it is only PCIe Gen 2

Moved to the Hardware Forum.

On the subject of Graphic Cards I recently read an article about how alot of GPUs are being sold for 2 or even 3x their MSRP.  Apparently this is due to a very high demand for crypto currency mining or something like that.  Basically this is bad time to be buying a Graphics Card.   Some companies that sell pre-built systems promise to sell for the MSRP.

Here's one article about it but just shop around & be careful about how much you pay for a card 

Graphics card shortage leads retailers to take unusual measures - Polygon

I think the system is ok but change the Graphics card. With only 1GB of memory you will be limited working with video. Try to select other graphic card with at least 4GB of RAM or even more if you think to work with 4K footage.