A prototype silicon microstrip detector for the GEM general purpose detector proposed for the Super Collider was assembled and tested in the laboratory with radioactive sources and an IR-Laser, and at SLAG in a 25 GeV electron beam. The system was designed for performance in the GEM environment: 60 MHz bunch crossing at 10(33) luminosity with inner barrel occupancies of 0.16%. Signals from the strips were amplified by custom designed high-speed, low-power, low-noise, low-mass, integrated microelectronics. The mechanical design of the GEM tracker motivated the selection of long (18 cm) strip lengths (achieved by wire-bonding three 6 cm long detectors). Evaluation of the test beam and laboratory results demonstrate the feasibility of this approach.