Neither will be good as a gaming rig, if that's what you want it for. A pair of 4650's can match around a 4770, maybe a 4850 at the right resolution. You'll have to change the GPU in the i7 system and would have to change pretty much everything from the other. The first system is based on, as cjl said, the OLD Pentium 4's on the 90nm process, so they'll be SLOW and run HOT! Plus, it may have 10GB of RAM, but it is ECC RAM, not for gaming use.
Agree, i7 hands down is much, much better.
If you are gaming, you could do better than crossfired 4650's. Someone has made the classic mistake of thinking 2 slow cards in Crossfire are as good a high end card.
But, you have a lot more to work with, and better upgrade potential, and just simply a much faster rig all around with the i7 build.