System apps are installed in system partition, all other apps are installed in data partition and every app you gonna install via market or manually will go to data partition (or sd card if enabled).
Hence, there's no benefit in deleting system apps... except if you wanna move some data apps to system partition afterwards...
All system apps reside in /system/apps. All you gotta do is remount rewritable and delete the apk and odex files you wanna uninstall.
You could also get Titanium Backup which will do that for you.
But be sure to read
https://wiki.mobileread.com/wiki/PRST...d_apk_packages