Is my pc is ready for CALL OF DUTY GHOSTS

Not quite. You need more RAM. CoD Ghosts needs at least 6 GB RAM. And your CPU probably meets the minimum requirements. You cannot play on high or ultra settings unless you have a quad-core CPU.

More RAM is recommended. However, since your hardware in general is outdated, it's probably not really economical unless you really aren't getting another computer to upgrade any parts. Here's the breakdown:

Your motherboard is an outdated G43 chipset from 2008. This greatly limits the selection of parts you can choose from.
- No new CPU's are available for this socket. The last few models that you could choose from were made in well, 2008. There are Core 2 Quads that you can buy used for about $150, but it's not worth the money for the relatively weak performance (vs today's processors) anymore in my opinion. Your Pentium Dual still should be okay because games are more video card reliant.

- Upgrading RAM is a problem. If you want to add RAM to the system, you will have to buy 4 identical 2 GB modules. You can't just mix and match (issues on the software side) or get one 8 GB stick because this motherboard is too old to support such a high capacity stick. 2 GB modules don't really exist anymore and can be even more expensive than modern day memory because it's a legacy part. What you have right now should be good enough to etch along with for now.

- The GTX 650 is a venerable performer, but it might lack memory (minimum today is 2 GB).

All in all though, you should be able to play COD decently on your PC at 720p. Just not at high settings perhaps. The card could be a little too weak for that. But maybe your PC can handle high. I don't know. The best way to up your gaming environment is to get a new PC when you have the money.

IF YOU DO DECIDE TO BUILD A PC:
As of 2014, what you would want in a decent PC would be something like...

Core i3 CPU/AMD FX 6300 CPU minimum, Core i5 CPU/AMD FX 8350 recommended
8 GB recommended, 16 GB or more best
GTX 750 Ti/GTX 760 for med/semi-high settings on most new games, GTX 770 and up for high settings on almost all new games

And don't just plug in a new graphics card like the ones I mentioned above into your current computer thinking it will improve performance. Your CPU and motherboard might not be able to utilize its power fully.

COD: Ghosts, a notoriously poor console port, is certainly not going to need 2 GB of VRAM at 1366x768.

Minimum System Requirements

OS: Windows 7 64-Bit / Windows 8 64-Bit
CPU: Intel Core 2 Duo E8200 2.66 GHZ / AMD Phenom X3 8750 2.4 GHZ or better
RAM: 6 GB RAM
HDD: 40 GB HD space
Video: NVIDIA GeForce GTS 450 / ATI Radeon HD 5870 or better
Sound: DirectX Compatible Sound Card
DirectX: 11
Internet: Broadband Internet connection and Steam and Online Multiplayer


Recommended System Requirements

OS: Windows 7 64-Bit / Windows 8 64-Bit
CPU: Intel Core i5 – 680 @ 3.6GHz
RAM: 8 GB RAM
HDD : 40 GB HD space
Video: NVIDIA GeForce GTX 760 @ 4GB
Sound: DirectX compatible sound card
DirectX: DirectX 11
Internet: Broadband connection and service required for Multiplayer Connectivity. Internet connection required for activation.

From this you can see that you would need more RAM as mentioned above, aswell as the cpu and GPU