would there be a big difference if I was to upgrade from an i3-2130 to an i5-2500k or i7-2600k?
If so, by how much?
also running a 6950 radeon card.
this would be for gaming mainly.
More aboutupgrade 2130
You will see a little bit of improvement if you are playing heavy CPU-bound games such as Dirt3 or BF3 Multiplayer going from an i3-->i5. You will see little to no improvement in games going from an i5-->i7 for gaming
BF3 on large multiplayer maps would benefit alot from the i5 other than that unless you are playing at a very low resolution there is little benefit except maybe a few CPU intensive games (none I know about).
Depends on the game. Your cpu is definitely not holding back your graphics card, so in most games you wouldn't see any improvement except in MMO's.
depends on the game but improvement will range from 0-5% generally with some games getting a bit more than that such as blizzard games.
You see some improvement, but not much unless there is a specific game you want to play that can take advantage of 4 cores.
At this point in time I would say to save up for a quad core Haswell that's coming out next year and motherboard for it. How much will a Haswell cost? Unknown, maybe around $240 - $250 for the unlocked quad core version.