if you have it already, then im not sure i would spend the money on the i5. With the new ivy series short to release, probably next month or for christmas time, i would not spend the money on a processor YET. But, i would recommend buying nVidia, as their mid-ranged cards outperform amd/ati's high-end cards more so than not. a good card, like a 460/560, will cost between $125-$175 after MIR. This will allow you to go with a higher end cpu when the newer IVY series releases from intel. This will be a much smarter upgrade in my mind, since you already own the i3.
no prob. if you give me a budget on total upgrade money, i may be able to find some "Best Bang for your Buck" items for you. Also, a description of what you are running such as your motherboard, psu, hdd/ssd, amount of RAM, and case would help immensely!
oh dear...lol, well thats a bit. hmmmm, are you an intel only guy? usually low budget pc's are built with amd cpu's and amd/ait gpus. I know i recommend nvidia but they are worth the extra money. amd to intel, unless you have a huge amount of money, amd i think is a better buy. What do you own now as far as case and psu?