PA32 PLT ENTERED AN INCORRECT WAYPOINT IN THE ACFT GPS NAV COMPUTER AND ENTERED A RESTR AREA AS A CONSEQUENCE.

Narrative

DURING AN IFR FLT FOR ENG (TEST/MAINT) OUT OF MTN; I WAS APCHING HEDGE INXTN AND CTR ADVISED ME 'AFTER HEDGE; GO DIRECT SALISBURY; THEN DIRECT SNOW HILL (VOR).' AS I DEPARTED HEDGE INTXN; I INADVERTENTLY ENTERED 'DIRECT SWL' INSTEAD OF 'DIRECT SBY.' A SHORT WHILE LATER; CTR INQUIRED IF I WAS DIRECT SALISBURY AND I ADVISED THAT I WAS DIRECT SNOW HILL (SWL). THE CTLR REQUESTED (VERY POLITELY) THAT I GO 'DIRECT SALISBURY (SBY)' TO EXIT THE ACTIVE RESTR AREA. I IMMEDIATELY EXECUTED A L TURN AND EXITED THE RESTR AREA; AND AS I DID; I SWITCHED THE GPS TO THE MAP-MODE AND NOTICED THAT I WAS; IN FACT; SKIRTING INSIDE R-4006. MOMENTS LATER; I WAS CLR AND NOTHING ELSE WAS SAID FROM CTR. SEVERAL THINGS CAUSED THIS ERROR; OF WHICH I AM TO BLAME: 1) I WAS RECORDING MANY ENG PARAMETER READINGS AND WRITING A LOT WHEN CTR GAVE ME THE CLRNC TO SBY AFTER HEDGE; AND I COMPREHENDED 'SWL' INSTEAD OF 'SBY' WHEN ENTERING THE NEW WAYPOINT; I WAS DISTRACTED ENOUGH. 2) SNOW HILL IS ALMOST IN LINE WITH SALISBURY; SO AS I FLEW FURTHER ALONG; THERE WAS NO ABRUPT HEADING CHANGE; TO ALERT ATC (OR ME) THAT I WAS 'DIRECT' TO THE WRONG VOR UNTIL I ACTUALLY STRAYED INTO THE CORNER OF IT (THE R-4006). 3) A QUICK REVIEW OF MY ENRTE CHART AFTER RECEIVING 'DIRECT SALISBURY' WOULD HAVE KEPT ME CLR; AND PROBABLY WOULD HAVE ALERTED ME TO THE WRONG WAYPOINT/PENDING INCURSION; ENOUGH TO INQUIRE ABOUT THE (WRONGLY PERCEIVED) CLRNC. 4) MONITORING THE 'MOVING MAP' PAGE OF THE GPS WOULD ALSO HELP; SINCE MOST RESTR/PROHIBITED AREAS ARE SHOWN.