Power Supply and Power Distribution System (PDS)

With a noisy or under-rated power supply, a circuit board is an expensive piece of garbage.

Family Primary Reference
Virtex™  5 FPGA Virtex 5 PCB Designer's Guide
Virtex 4 FPGA Virtex 4 PCB Designer's Guide,
Virtex 4 User Guide
Virtex II, Virtex II Pro XAPP623