I went to pcpartpicker.com and did some digging around. You wanted better performance, so I wanted to get you up to an I5 4 core cpu. These are about as good as you can get on the budget you have. I also looked for an H97 motherboard with good user feedback (4.2 stars out of 5) since this CPU cannot be overclocked and as such these boards support the Haswell CPU's without the overclocking features, so they cost less.
Your memory and other components should work fine with this board. But you could also get faster memory if you wanted. Your current motherboard only supports 1033/1333 speed RAM. The motherboard I linked here should be able to use 1600 (and possibly faster) RAM.
http://pcpartpicker.com/list/7FMw7P
Intel Core i5-4460 3.2GHz Quad-Core Processor
$169.99 $169.99 SuperBiiz
Motherboard
ASRock H97M PRO4 Micro ATX LGA1150 Motherboard
$69.99 $2.99 $72.98 Newegg
Base Total: $239.98
Shipping: $2.99
Total:
$242.97 . . .
Prices can and often do change daily. Check the link above for current prices.
Hope that this helps you... Enjoy!!