If you're outside of the US (I'm guessing, based on the speed of your link), some products are export-restricted. You'd have to check on support for your locale. Another option if you're in a DIY mood is making a custom Linux box using split access features of iptables [3].
[1] http://www.newegg.com/Product/Product.aspx?Item=N82E16833124...
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...
Perhaps I should blog about the setup as some point.
You just bond the two public facing nics together with ifenslave, setup pppoe and write an iptables script.
Also, IIRC (been a while since I did it), normal bonding only gives you round robbin i.e. your max speed is limited to the bandwidth of whichever external link your connection is forwarded through at the time (unless you use an ISP that can do MLPPP - which is rare). If you want to combine the bandwidth of both connections into one fat virtual pipe, you could get a cheap VPS and then run an Open VPN link over the bonded virtual interface on your linux box at home to the VPS box (I think! I last played with this 4 yrs ago and details are hazy...).
Then you have to get or guess the configs for both WAN links, possibly with unhelpful residential support techs.
Cisco 2600 class routers are power hungry and loud too, so no win there. Soekris is smaller and more efficient, and runs BSD, so it's awesome in other ways...but it is a pain in the neck to set up. Several hours of prep plus work for your first time.
But if you are most concerned about DNS, I can think of two quick options: put your own router (ideally running Tomato or DD-WRT) behind your existing mess and serve DHCP from there to your network(s), or take DHCP from your provider, but hardcode the DNS settings on each host.
Edit: and Aside: less than a minute after posting this, I decided to check google to see if Soekris supported cable modem cards, and my post (this comment) came up on the first page of results. I had no idea google could turn crawls into results that quickly.
But it appears that Soekris does not support cable modem cards, from a cursory investigation.
Or if you're lucky enough for your provided devices to support real bridge, put both of your devices in dumb mode and plug that as ethernet into your dual-wan device. That's still hardware present but management is kept to the absolute minimum. Plus sometimes you don't really have a choice to use the provided devices...
BTW, do yourself a favor and don't get a Zyxel device.
http://www.netgear.com/business/products/security/wired-VPN-...
It's not as sexy as the FOSS solutions on this thread, but it has the advantage of working just by plugging in power and two Ethernet cables.