I don't know about samba.
But you can easily check of what you need included in your custom kernel. Connect every possible hardware you will ever connect to this PC (irda, bluetooth, lirc), use any user level tools you intend to use (sensors, monitoring stuff).
After that invoke lsmod | sort. Write it down to something ( a file ( lsmod | sort > file) or write it down on a piece of paper
Some things are necessary even though they are not actually loaded so if you are not sure leave it as module or google it to make sure you can throw it away. Enable debug mode while using make xconfig, it will show you the dependencies of the modules like A depends on B.
You can safely get rid of some specific drivers for specific hardware (just read read and once again read ). You can cut on compilation greatly that way. You can get rid of many audio and video drivers if you know which ones you need
I always have my audio built in, that way i never had problems with audio after that though yast2-sound won't work

(but you won't need it anymore after that).