If you don't want to mess with iptables, ClearOS (CentOS derivative) [1] has built-in multi-WAN support [2], including auto-failover and load balancing. There's a GUI, but you can always SSH in and configure things manually.
My home router/server is a MicroATX box with an Atom D525, 4GB RAM, 2 x 1TB RAID-1, and 2 x Gigabit NIC. Cost a few hundred dollars to build, draws ~16W idle, and is almost silent. DNS, SSH, FTP, SMB, POP/IMAP, SMTP, QoS, PPTP/OpenVPN/IPsec, and dmcrypt are included. The Atom chip is fine for home use, move up to an Athlon if you're pushing a lot of SSH traffic.
My home router/server is a MicroATX box with an Atom D525, 4GB RAM, 2 x 1TB RAID-1, and 2 x Gigabit NIC. Cost a few hundred dollars to build, draws ~16W idle, and is almost silent. DNS, SSH, FTP, SMB, POP/IMAP, SMTP, QoS, PPTP/OpenVPN/IPsec, and dmcrypt are included. The Atom chip is fine for home use, move up to an Athlon if you're pushing a lot of SSH traffic.
[1] http://www.clearfoundation.com/Software/overview.html [2] http://www.clearcenter.com/support/documentation/clearos_ent...