I use Verizon DSL on Linux and it works perfectly fine. To answer your question, yes, you do need to be root to establish a PPP connection (which is what ADSL uses, via PPPoE). I put adsl-start in the startup script on my router so that the Internet connection starts when it is booted and I don't have to worry about it. If adsl-start is succeeding, chances are you're set to go. If you're having problems, post the results of /sbin/ifconfig -a and try to ping a host on the Internet by name and by IP address (try www.google.com
and 188.8.131.52). If you can ping by IP but not name then the issue is with DNS. Verizon distributes DNS server info via DHCP, but this did not work correctly for me when I first set it up. Running 'dhcpcd eth0' (no quotes, assuming your net interface is eth0) fixed the problem for me.