A build with a X4 955 and an equivalent AM3 board (Gigabyte GA-790XTA-UD4) would have made the total cost of the build $1,022, if you were interested in looking into an AMD build. Of course, that's only dropping to AMD's top of the line CPU. If you really wanted to save some money, the X3 425 can be had for $70 (another $90 of savings) and also wouldn't drastically affect performance.
The i5-750 build would have better performance right now, but there isn't much room for upgrading the CPU. Intel is moving the LGA1156 socket into the mainstream, meaning instead of making high powered CPUs for the socket they're going to be making low powered cheap CPUs.
The X4 955 build would be slightly lower performing right now, but has more upgrade potential. The AM3 socket is going to be AMD's main socket for the next couple of years. The socket will see the upcoming six core CPUs (not that you'll need them for gaming) and likely whatever is coming after that.
That said, you shouldn't feel bad with either the i5-750 or X4 955 builds. They're both great gaming machines, and you shouldn't need a CPU upgrade for a long time.