I've been using FSX for some years ( close to 5 years now ) and was thinking about switching to P3D. But my problem is my pc specs aren't so good:

 

Intel i3 2120 @ 3.30 GHz

4 GB RAM

GeForce GT620 1GB

Windows 7 Home Premium 64 bits

 

Can I run P3D with this specs? 

 

P.S- I have around 25-30 stable fps on FSX 

You can run P3D of course but you cannot expect fps like in FSX because your GPU and CPU are very weak.

You should stay in FSX until you upgrade your pC

There's probably no advantage as you will have to reduce the image quality settings in P3d to those that roughly match FSX. FSX was designed for your system. P3d will run on your system, but to bring out its best points, it needs more advanced hardware.