C560XL flight crew overshot altitude on departure from DWH when they complied with the SID altitude restriction not the clearance limit.

Narrative

Obtained clearance from DWH. Initial Altitude was cleared to 2;000 FT MSL; and was written down. Using our 'Electronic Charts' on our Garmin GMX 200 was unable to obtain the graphic for the El Dorado 1 DP from DWH; due to some sort of database error we believe due to some sort of mix-up from the database supplier (looking into this). In the meantime; booted up the EFB laptop we have as our second source of NAV data. Found the DP and the initial departure altitude of 4;000 FT as published. Started engines; and turned Avionics ON. Set altitude alerter to 4;000 FT. On climbout; was informed of our initial altitude assignment of 2;000 FT while passing through 2;700 FT. Was asked to level at 3;000 FT with no further issue. I believe the situation could have been avoided using a few simple procedures. First; the written clearance should have been placed in a more conspicuous location; so as to be available for quick reference of initial altitude and heading prior to the takeoff roll. Prior to the takeoff roll; the altitude and heading should always be re-confirmed. Simply checking and double-checking the cleared altitude prior to takeoff would have eliminated the situation completely. Contributing to the mix-up was the usage of the electronic charts that were not readily accessible. The time delay in finding the DP along with not having the clearance in plain view both contributed to the deviation. In the future; the clearance will be written down (as it was in this situation); posted in a conspicuous location where both crewmembers can see it; and both heading and altitude CONFIRMED prior to the takeoff roll.