With the Rasbian image, you can re-run the initial start up script using:

$ sudo raspi-config 

and entering your sudo password.

This will bring up the same menu options that you got after first boot.

You do not need to remake all your first boot choices, just use the arrow keys to move to the menu options you want to change.

In your case, selecting:

Start X-server after boot?

and choosing:

no or disable

will sort you out.

Editing to add non gui based options:

As noted in the comments below by @mirk, the exact command for the raspberry is:

sudo update-rc.d lightdm disable 

With the Raspbian image, you can re-run the initial start up script using:

$ sudo raspi-config 

and entering your sudo password.

This will bring up the same menu options that you got after first boot.

You do not need to remake all your first boot choices, just use the arrow keys to move to the menu options you want to change.

In your case, selecting:

Start X-server after boot?

and choosing:

no or disable

will sort you out.

Editing to add non gui based options:

As noted in the comments below by @mirk, the exact command for the raspberry is:

sudo update-rc.d lightdm disable 

With the Rasbian image, you can re-run the initial start up script using:

$ sudo raspi-config 

and entering your sudo password.

This will bring up the same menu options that you got after first boot.

You do not need to remake all your first boot choices, just use the arrow keys to move to the menu options you want to change.

In your case, selecting:

Start X-server after boot?

and choosing:

no or disable

will sort you out.

With the Rasbian image, you can re-run the initial start up script using:

$ sudo raspi-config 

and entering your sudo password.

This will bring up the same menu options that you got after first boot.

You do not need to remake all your first boot choices, just use the arrow keys to move to the menu options you want to change.

In your case, selecting:

Start X-server after boot?

and choosing:

no or disable

will sort you out.

Editing to add non gui based options:

As noted in the comments below by @mirk, the exact command for the raspberry is:

sudo update-rc.d lightdm disable