My cpu has intel pentium(R) dual core e6700 processor at 3.2 ghz and Ecs g41t motherboard . I am planning to insert a Nvidia gt 730 graphics card . Will it be adequately supported by my processor?
I think It'd be fine, it's all about how nice of a gaming experience you want. Duo-Cores, 3+Ghz is not bad, could run mostly anything but a quad-core will make your FPS more 'liquid'
In that case should I go for a 1gb ddr3 ( possibly a gt 610 ) gfx card for now and go for the gt 730 when I've got an i5 and a new motherboard ?
Again, it will depend a lot on the resolution of your display. Neither of those cards are really considered gaming gfx cards. The GT 730 is by far the better of the two, though. IF you get the DDR5 version. Here is a short read that may help you out: http://www.tomshardware.com/reviews/gaming-graphics-card-review,3107-2.html
If you are planning on upgrading your system to an i5 platform in the near future, you should get as much gfx card as you can afford. It won't matter if it is too powerful for your current system to make full use of, because you will be moving it to the new system later.
There is one caveat, however. Your power supply. If you get the GT 730, 740, or even the GTX 750, you will be fine with most OEM PSUs that are usually ~300W.