modconf is the Debian text-based GUI utility used to manually choose which kernel modules (ex., hardware drivers) get automatically loaded at startup. You would use modconf rather than hand-editing config files or using the modprobe command.
That said, most distro's use some sort of automatic hardware detection. Redhat-based distros typcially use kudzu while Debian-based systems usually use discover. On these systems, you almost never have to manually load modules. These days, I think you'd only use modconf in a pinch, say, if discover wasn't able to detect some specific out-of-the-ordinary device.
Q. What would you use with other disributions like SuSE?
A. Most distros these days use automatic hardware detection. If yours doesn't, or it's just not detecting your hardware correctly, you're stuck with figuring out which module needs to be loaded, then using modprobe to load it (you may also need to hand-edit some config files in /etc).