I would say if you want to purchase Slackware, do it straight from their website.
It looks like the CD set only provides the 32 bit version, and the DVD has 64 bit Slackware as well. Beyond that, they should be pretty comparable.
Drivers for linux are usually included in the linux kernel, so it is rare to have to go searching around the web for them. In some cases, primarily with wireless cards, you may need to install extra firmware for a driver or build a newer version of a driver to work properly with your hardware. But the vast majority of hardware works effortlessly.