National Instruments has an SDR platform: the NI PXIe-5641R RIO IF Transceiver

  • based on a Xilinx Virtex5SX95T FPGA, 20MHz bandwidth
  • up-converter with a range of 250kHz-2.7GHz on a 25MHz IF
  • down-converter with a range of 9kHz-2.7GHz on a 15MHz IF
  • they will also sell you a dual-core PXIe WinXP PC
  • LabVIEW + FPGA module
  • extra modules for modulation and digital filters