not even a virtual hardware, just a nic that supports 802.1q and a vlan capable switch! In theory a single interface is all that's needed with the right hardware. There is a story online where a guy took a computer with two nic's (one lan, one wan) a vlan switch and load-balanced across 6 DSL connections for a gaming center using pfSense.

Unless you can get your ISP to bond several connections together about the best you can do is load balancing across multiple connections. I use pfsense (http://www.pfsense.com) as my router/firewall VPN solution that's free, you only supply the hardware to run it on. with it you can load balance and fail over to 2 or more connections automatically. Specif connections can even be setup to have certain traffic routed over them while all other traffic gets load balanced round robin style. there are of course other free *nix distros out there that will let you do the same type of stuff however I and many others have found pfSense to be far batter than most. AW

http://www.stikc.com/ Pick up a used server. great people. (I don't work for them)