Hello billygfx, and welcome to CDRInfo.com.
To backup games to optical media be it CD or DVD you will need a mod chip or swap discs or the like... The PS2 Network add on is only required if you want to add a HDD or play online PS2 games.
Let us know what you would like to do, be it a HDD, optical media backups or both? A HDD decreases those painful loading times, and is said to improve the graphics in some cases also, while also allowing you to store multiple games/music/video on your PS2 console. Optical media backups offer the simplicity of recording your games to recordable DVD or CD.
Please be a bit more elaborate on what you are lookin to get out of this.