By all means buy a monitor/alarm thingy that goes off if your baby stops moving/breathing.
Get an audio monitor if you are going to be along way from your baby's bedroom (like I'm on the ground floor and my daughter is on the second floor)
Other than that, if your baby needs you it will let you know.
Don't worry/panic to much, checking on the baby every 5 mins won't do yourself or the baby any good.