A G200 AT 2200 FT DEPARTING BED IDENTED C172 TFC AT 3000 FT BUT RECEIVED AN RA FROM AN UNIDENTED PA32 AT 2000 FT COMMANDING A 2000 FPM CLB INTO THE C172.

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WE DEPARTED BED AT XA01Z ON OCT/THU/05 ON RWY 9. TKOF CLRNC WAS FLY RWY HDG TO 2000 FT. DURING THE CLB; TWR ADVISED XING TFC L TO R AT 3000 FT AND HANDED US OFF TO BOS APCH 124.4. WE VISUALLY IDENTED A SE C172 AT 3000 FT HEADING N. BOS APCH ISSUED A R TURN TO 050 DEGS AND CLB TO 3000 FT. I STARTED A R TURN TO 050 DEGS BUT ONLY STARTED A SLOW CLB TO 3000 FT DUE TO THE CESSNA AT 3000 FT APPEARED TO BE A CONFLICT. WE WERE UNABLE TO CONFIRM THE CLB CLRNC DUE TO FREQ CONGESTION WHEN; PASSING 020 DEGS AND 2200 FT WE RECEIVED A TFC ALERT IMMEDIATELY FOLLOWED BY AN RA TELLING US TO CLB AT 2000 FPM. I STOPPED THE TURN TO PARALLEL THE LAST VISUAL HDG I HAD ON THE CESSNA BUT CONTINUED A SLOW CLB. ABOUT THE SAME INSTANT; I SAW A SINGLE ENG PIPER (SARATOGA) AT 11 O'CLOCK POS HEADING E AT 2000 FT. WE PASSED SLIGHTLY IN FRONT OF THE SARATOGA AT 2400 FT AND LESS THAN 1/2 MI. BOS APCH WAS VERY BUSY AT THE TIME AND WE WERE HANDED OFF TO THE NEXT SECTOR BEFORE WE GOT TO 3000 FT OR THE CHANCE TO GET AN EXPLANATION. WHILE THE TCAS ALERTED US TO THE LOWER ACFT AND CORRECTLY INDICATED A CLB; I AM CERTAIN THAT IF I HAD FOLLOWED THE RA CLB RATE IT WOULD HAVE CAUSED AN EVEN CLOSER ENCOUNTER WITH THE C172. I'M NOT SURE WHAT THE OUTCOME WOULD HAVE BEEN IF WE WERE IFR AND FOLLOWING THE RA.