You don't tell us enough to really help you here, but I can tell you that your design as diagrammed is for all intents and purposes completely wrong (or vastly oversimplified, so as to lose all relevant information and thus be completely wrong).
As diagrammed you have no separation between internal and external networks (you're glomming everything into the same switch, presumably the same VLAN) which effectively negates any potential security benefits you might be hoping to gain - the only thing you might gain is performance if you routinely saturate one of the NICs (and that could be achieved through other methods).
To have any semblance of proper separation you need two switches (or two separate VLANs on a switch that supports VLANs). Internal communication should be completely isolated from external communication, as shown here
Note that from a security standpoint even this illustrated configuration is still a terrible one. With a few rare exceptions you should never have a computer in the situation illustrated above (dual-homed with one NIC on the inside network and one NIC on the outside network) because it is a HUGE security risk: If someone compromises that machine they now have access to your internal network.
A better configuration would be a proper DMZ with restricted access through a firewall to internal resources.