Is the 300ghz difference worth the 40 dollars? Also, i am intending to use the on-board graphics so is the i3-2130 a better choice in this case? I will be using it for work,surfing,video and light gaming.
You probably want to consider the Core i3 CPU models ending with the number 5 if you want to rely on the integrated graphics core. Basically there are two different graphics cores, the Intel HD 2000 and the Intel HD 3000. Only the "higher end" CPUs have the faster Intel HD 3000 graphics core. That includes the Core i5-2500k, Core i7-2600k and all Core i3 CPU models ending with the number 5.
The Core i3-2100 comes with the Intel HD 2000 core while the Core i3-2105 comes with the Intel HD 3000 core. The CPUs both run at the same speed though.
The Intel HD 3000 graphics core is marginally more powerful than the desktop Radeon HD 5450 graphics card. That puts it at 2x (or more) powerful than Intel's old GMA 4500 graphics core which is really bad for games. The Intel HD 2000 graphics core is probably about 50% more powerful than the GMA 4500 at best.