BE55 pilot reports deviating from the NOTWN2 departure from VGT due to possible malfunction or incorrect programing of new glass flight displays.

Narrative

The problem arose after I departed Runway 25 at VGT. I immediately noticed that the flight path did not display on my GPS screen nor on my PFD Flight Display. The Las Vegas Approach Controller asked about my incorrect flight path. I had made a right turn but did not have NAV steering to the published 313 degree radial. I was told that I was not on course. My onboard GPS displayed RUZCO Intersection to the west and I steered to it. Upon crossing RUZCO I executed a turn to the right to reverse direction to LAS VORTAC which was the next fix on the SID. My altitude was in a climb to 5;000 FT MSL. ATC said I was not on the published LAS radial of 320 degrees and gave me a heading. The rest of the flight was uneventful except that in the vicinity of the BLD VORTAC; ATC gave me a number to call after landing. I called and was told that a pilot deviation had been filed by the previous controller; who was now off duty. I had been scheduled for a recurrent training program. It includes ground school with a heavy concentration on GPS systems; and 4 hours of instruction in the pilot's airplane. Use of the GPS/PFD Flight Display was covered in detail. My perceptions with regard to this incident are that I should always have ready VOR backup in the event of glass panel failures/problems and that more frequent training opportunities are very important. Factors affecting my performance include that I was in transition from a King/PN-101 system to the GPS/PFD Flight Display; and I was just beginning to use approach plates on a tablet. One action not taken was to cancel IFR at the first instance and return to VGT for situation analysis on the ground. I completed the recurrent training program successfully and have a fresh biennial and instrument competency check. I am confident that I am now able to more effectively deal with this type of problem; be it equipment and/or human factors.