Just out of curiosity, would it be legal for us to use an I-5 cRIO on our FRC robot next year?
The (primary) cRIO must be one of the two FIRST specific models.
R55
ROBOTS must be controlled via one (1) programmable National Instruments cRIO (P/N: cRIO-FRC or cRIO-FRCII), with image version FRC_2013_v47.
Can an I-5 processor be used on the FRC specified cRIO?
No, the FRC cRIOs are PowerPC based.
An i5 could be used as a co-processor reporting to the FRC cRIO. It just can’t directly control the robot. It must send commands through the FRC cRIO.
I see. Thank you very much 
Next year’s rules have not been written, so no one knows.
Based on this year… probably not, or not as you intended. It could be considered a custom circuit or coprocessor, but then it can not control any motor controllers, or interface with the power pathways.
R54
Custom circuits shall not directly alter the power pathways between the ROBOT battery, PD Board, motor controllers, relays, motors, or other elements of the ROBOT control system (including the power pathways to other sensors or circuits). Custom high impedance voltage monitoring or low impedance current monitoring circuitry connected to the ROBOT’S electrical system is acceptable, if the effect on the ROBOT outputs is inconsequential.
Expanding on Mark’s R55 This is the blue box explanation.
There are no rules that prohibit co-processors, provided commands originate from the cRIO to configure, enable, and specify all operating points for all power regulating devices. This includes Jaguar motor controllers legally wired to the CAN-bus.
If the I-5 has outputs, then you are bound to R72 (Blue box included)
R72
All outputs from sensors, custom circuits and additional electronics shall connect to only the following:other custom circuits,
additional COTS electronics,
input ports on the Digital Sidecar,
input ports on the Analog Breakout Board,
the RS-232 port on the cRIO,
the Ethernet network connected to either Port 1 or Port 2 of the cRIO,
the CAN-bus if and only if all Jaguar motor controllers on the CAN-bus are wired in full compliance with R68 and R69, or
the sensor inputs on the Jaguar motor controller.Custom circuits and additional electronics are allowed to utilize the Port 2 Ethernet bus on the cRIO-FRC and/or the CAN-bus to communicate between devices. Note however, that the ROBOT must be controlled by the cRIO (see R55). Thus, any additional devices on the Ethernet or CAN-bus must not provide command signals that do not originate from the cRIO.
And I don’t know what an I-5 cRio is but I have a suspicion if it is like most NI hardened processors, you will issues with the budget rules, particularly Rule 11.
R12
No individual item shall have a value that exceeds $400 USD. The total cost of COMPONENTS purchased in bulk may exceed $400 as long as the cost of an individual COMPONENT does not exceed $400.
It should be around $8k of a NI CRIO-9082 8 slot 
OP, if you really need the Intel i5 processor, you can get a mini-ITX based solution and run it as a coprocessor. You’d be hard-pressed to fit it under the $400 price point, though. There’s also nothing in FRC that requires the power of an i5. You can easily do vision processing using the ARM processor architecture found in a smartphone, Linux, and OpenCV.
I guess I took too long editing my post?
You must have 
I knew how much it cost as soon as I opened this thread since I’ve been looking at purchasing a variety of NI goodies for work.