B737 CREW DEPARTING DFW DOES NOT INSERT REQUIRED SID TRANSITION INTO FMC AND GETS OFF COURSE.

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I GOT DISTR. IN A NUTSHELL; WITH A LATE ARRIVING AIRPLANE AND A BUSY BOARDING PROCESS; PRIOR TO CHKING OUR RTE 'GLASS TO PAPER;' I RECEIVED A PHONE CALL THAT I HAD BEEN ANTICIPATING. AFTER HANGING UP; THE FO AND I PROCEEDED TO 'GO THROUGH THE RTE' FOR THE CLARE 2 DEP OUT OF DFW WHERE I WAS KEYING IN ON THE FIRST PORTION OF THE SID. ASSURED THAT WE HAD THE RIGHT RWY AND THE FIRST POINTS; I OVERLOOKED THE FACT THAT THE GLASS DID NOT CORRESPOND 'ENTIRELY' WITH THE FLT PLAN AND MISSED THE SWB TRANSITION. (MY THOUGHTS TILL BEING 'DISTR' BY THE PHONE CALL.) AIRBORNE; AT CLARE; INSTEAD OF MAKING THE TURN TO THE CORRECT FIX; WE PROCEEDED TOWARD SWB. ZFW QUERIED US IF WE WERE PROCEEDING TO TEKBE. THE FO INITIALLY SAID 'YES' BUT THEN REALIZED THE PLANE WAS IN FACT GOING TO SWB. CTR GAVE US A HDG AS WE QUICKLY REINSERTED THE SWB TRANSITION INTO THE BOX. THIS WAS A GOOD 'GOTCHA.' I WAS HIGHLIGHTING THE FIXES NEAR THE ARPT AS BEING 'MORE IMPORTANT' THAN THE PERCEIVED 'NON THREAT' FIXES DOWN THE ROAD. THE MILEAGE AT THE END OF THE FLT PLAN CORRESPONDED ACCURATELY WITH THE GLASS NUMBERS AND I MADE AN 'ASSUMPTION' THAT 'WE WERE FINE.' I WILL ADD THIS TO MY TOOL BOX IN FUTURE FLTS.