Look, for gaming, the INTEL i3 3220 along with B75 chipset Motherboard based configuration is best. There are certain CPU intensive games where the Non-HT Pentium G645 takes a big hit in performance. The latest game Far Cry 3 is perfect example of it. At 1080P resolution, the G645 was more than 15 FPS lower than i3 3220 and 2120 when paired with a powerful Graphics card. Also B75 based motherboards are far better than H61 based ones and the extra 1 to 1.5K you pay for it is well justified. It offers high speed and higher capacity Ram support, better build quality, more number of expansion slots, necessary features like USB 3.0 and SATA III 6 Gbps support.
However, one problem with future proofing with Intel rig. Intel is going to launch their Hashwell processors next year which will be based on a complete new socket, LGA1150. So none of the current generation platforms will be compatible with it.
Now I am giving you an configuration based on AMD's Trinity, the latest APU. I think you're aware that APU stands for Accelerated Processing Unit which packs a powerful CPU and a very powerful IGP inside a single silicon die. The IGP of Trinity Processors can match the performance of a 4K discrete Graphics card. Also the flagship Trinity Processors A8-5600K and A10-5800K are quad core processors, offering almost same gaming performance as an i3 3220 and better multi-tasking capabilities.
AMD A10-5800K (3.8 GHz, 4 Cores, 4MB L2 + 8 MB L3) @ 8.4K (Flipkart)
ASUS F2A85-M-LE @ 5.7K (smcinternational.in)
Transcend JetRam DDR3 8 GB PC RAM (JM1600KLH-8G) (8GB X 1) (5 years warranty) @ 2.35K (Flipkart)
Corsair CX 430V2 @ 2.7K
CM Elite 361 @ 2.35K (Flipkart)
Total: 21.5K.