ii49, no, you don't need this to share DSL between your two modems
but, if you look at your other options, there's intalling two network cards in one of your boxes and hopefully having enough irq's, running the most temperamental internet connection sharing and as always, hoping that this all works with PPPoE or whatever protocol you gotta deal with and blah, blah, blah, blah, blah, two to three days of configuring and nothing works together, pulling your hair out, blah, blah, blah, blah
this router is a breeze to install, it's got a nice little firewall, built-in PPPoE support and the print server is a nice little bonus..
necessary, no, worth it, YES