Exchange server question

at my company we have an exchange server running through an ironport filter.. i was just curious because we are about to have to upgrade to a newer firmware version.. boss man was talking about taking it down once busines slowed down one evening to reconfigure the nic cards.. right now it has 2 nic cards but only one is being used.. it has all info going in and out of the one.. but when we upgrade we are going to have one card going into the network for our internal email and another going out to the internet.. but we were kinda partial to this idea cuz even though its supposed to have a built in firewall.. wouldnt it be more possible for someone to hack their way through now that we would have 2 points of failure instead of just the one... wouldnt this open the door to the internal network?

lol i guess this isnt really a current problem.. more of i was just curious for more info...

thx for any replys