Only real way to tell is to build a brand new rig and then upgrade your current one and test them side by side =P.
Of course the new one will always be faster, new parts, better processor, RAM, HDD, and GPU, but it is also more expensive.
"Truth is violated by falsehood but outraged by silence."
"Mastering others is strength, mastering yourself is true power." ~Sun Tzu
"Ad Astra Per Aspera"
"Our greatest glory is not in never falling, but in rising every time we fall." ~Confucious
"The true measure of a man is how he treats someone who can do him absolutely no good.” ~ Samuel Jackson
“Omnis vir est fortunae faber”