hi voonz

basically installer and cydia is almost the same thing..both are installer of the 3rd party apps apart from cydia where it does more than installing apps for you. So basically you dont have to have both apps and cydia is way recommended to be use as its more stable and more apps are in it..further to it cydia will automatically transfer your fonts, ringtones and apps to the /app folder instead of /root and it will free more space in your /root..

Repawn your iphone and only install cydia..

hope this helps you..

to sifu's correct me if im wrong