Currently Im hosting 2 domains off my plug and have never had a problem. Mostly it is for personal use (ssh and a couple of web apps) but sometimes Ill put files up for friends and family to grab. The plug has plenty of power to handle a lot more traffic though.
I suppose not running the network start up script is in fact a bad idea as a lot of stuff relies on the loop back interface (lo). Under /etc/sysconfig/network-scripts edit ifcfg-eth0 and set ONBOOT=no.
And sorry if this is the wrong path. I dont have my ubuntu box on again and only have access to CentOS boxes atm. 'find / -name ifcfg-eth0' should get the path for you.