I wound up ordering all of the High-side transistors from Digi-key. I found 4 N-Channel MOSFET transistors at my local radio shack though.
After much trial and error, I had a breadboard circuit with a working H-Bridge. Much to my surprise it actually drove the motor when I ran my test sketch.
Other speeds and directions were not making it through the circuit properly though. As it turns out, these were IRF510 mosfets which aren't really supposed to act as relay switches. I read some articles online which directed me to the datasheets. The Vgs / I curves told the tale. Even though the Vgs of the Mosfet is rated at 2-4 volts, that is only for circuits with really low current. The MOSFETs had no problems turning on, problem was, they would stay on. Placing a 10k ohm pull down resistor on the mosfet kept the gate closed with the Arduino signal voltage.
So, what is the difference between the IRF510 and the FQP50? I noticed that the FQP50 has 'L' in the model number which supposedly means it's a logic level transistor. The IRF510s promise fast PWM switching but why such a high voltage transition to switch the gate? My only assumption would be that with a high Voltage differential you would have more current to do whatever happens to open a transistor gate faster. Just guessing though.