This is a simplistic benchmark, but it gives you an idea in the difference in speed. (Passmark numbers used below)
http://www.passmark.com/index.html
BE-2350
Min Score is 649 in single thread scenarios.
Max Score 1031 in 100% multithread scenarios
One of the newest but cheapest intel processors is G1620 that your friend has, here is the performance
G1620
Min Score is 1453 in single thread scenarios
Max Score is 2682 is 100% multithread scenarios
So your friend cpu is about 2.5 times faster for it does the work in 38% of the time.
Here is your cpu support list for your board. Looking it over here are the fastest cpus your board can do.
AMD 980 Quad Core at 3.7 ghz
Min Score is 1323 in single thread scenarios
Max Score is 4668 in 100% multi threaded scenarios
AMD 1100t Six Core at 3.3 ghz
Min Score is 1270 in single thread scenarios
Max Score is 5912 in 100% multi threaded scenarios
Note even your friend budget cpu, is faster in single threaded performance.
That said if you are looking for a cheap upgrade, any amd AM2 or AM3 cpu that is compatible with your motherboard and is a quad core at 3 ghz or higher will be a massive upgrade. Don't waste money on getting the best like the 980 or 1100t for you will have diminishing returns and the rest of the computer like your motherboard, ddr2, and hypertransport will slow down even those cpus potential. Something like an amd quad core at 3 ghz or better. Here is the numbers for the
AMD 640 Quad Core at 3.0 ghz
Min Score is 1027 in single thread scenarios 58% faster than your current cpu
Max Score is 3349 in 100% multi threaded scenarios. 224% faster than your current cpu.
That said I would not spend more than $60 dollars on any used cpu for your computer.