A late runway change and a high ATC assigned airspeed caused a flight crew to initiate a go-around due to their inability to achieve a stabilized approach. A newly installed cockpit NAV display may have contributed to the flight crew's loss of situational awareness.

Narrative

Approach Control assigned as an airspeed of 190 KTS to NAYIB Intersection approximately 10 miles from the 26R runway threshold at 3;000 FT MSL. The autopilot was engaged in LNAV/VNAV. Inside NAYIB and descending on the approach; slowing and configuring the aircraft; we were switched to MIA Tower. Upon initial contact the Tower Controller instructed us to change to and land on Runway 26L. This was not a request but an instruction. We could have declined the clearance but we chose to comply with the instructions received from what we perceived to be an overloaded Controller.Because of the assigned airspeed at NAYIB and the threshold for Runway 26L being 2;000 FT closer to our aircraft than the threshold for 26R; for which we had already established an appropriate descent profile; the change in runways put us high for a stabilized descent for 26L. It became apparent that we would not be able to comply with the stabilized approach criteria and touchdown zone requirements. A go-around was initiated but not until we had descended below 1;000 FT AFL (Above Field Level). This was because of the delay in situational awareness in airspeed and altitude due to the lack of experience flying with the newly installed NAV display. If we had been landing to the east on Runways 8L or 8R the change in runways would not have resulted in a go-around as the runway thresholds are adjacent. The offset thresholds of Runways 26L and 26R immediately put an aircraft established on a normal descent profile for 26R high when switched to 26L.When complicated by having to hold an assigned airspeed higher than optimal from Approach Control close in to the airport it prevents the pilot from having the ability to comply with this runway change and maintain a stabilized approach. The go-around itself is an issue in this situation as it is now tower controlled and has the potential of conflicting with departing aircraft off of Runway 26R.