How to disable xserver autostart?

[shaggy999]

I've got xubuntu installed on an old PII 333 MHz w/ 160 MB of RAM, but I would prefer to stick to a terminal unless I actually need to run a graphical program. So what I'm wondering is how do I keep xserver from automatically starting?

[soxs]

decrease default runlevel

normally it is defined in /etc/inittab, but ubuntu doesn't use this config file anymore.

So you will have to append a grub setting like:
init 3