going to mexico in july and unsure about the airlines...

[JessKa]

hey im going to mexico for 3 weeks in july and my boyfriends dad booked the flights already and bein a scared flyer i usually fly on what i consider the safest airlines i know. but this time he has booked airlines im not familiar with. We are flying on a Delta airlines 767-400 to atlanta then a aeromexico 757 to cancun, then we fly aeromexicos 737, md80 and embraer 145 around mexico. im just curious do these airlines have a good safety record? have they had any serious accidents in the past decade? what is the airlines quality? im really anxious about these flights and im more scared on the smaller planes then the big ones. is the 767-400 a pretty big plane? and what the history of the embraer 145 and the md80? are they good planes?