suyash45 :
This Is My Old Rig
Techcom 450 watt psu 10 amps
Intel E2200
INTEL DG31GL MOBO
I AM BUYING NEW E8400 AND ZOTAC GT 610 2GB DDR3 Synergy Edition Graphic Card
Is my MOBO AND PSU Compatible With It
Yes, they are all compatible.
The E8400 will directly swap with your E2200 as they are both LGA775 chipset. Just make sure you update the bios before changing the processor, or the motherboard may not recognize the new processor.
The new video card only requires a 300 watt power supply, and does not have external power requirements, so you should be fine with that.