[thamer]

The first time I installed a minimal Gentoo (~2005 or so) I could boot to a shell with 17 MB of RAM used. This was after tuning the kernel to make it as small as possible and removing everything I didn't need, disabling all superfluous init services, etc.

It's quite possible that it did use more than 17 MB temporarily before going back down, but I would expect that it's probably doable in 32 MB + swap.

Configuring a minimal Linux system with Gentoo or Linux From Scratch is a great way to learn how things work (especially learning from mistakes like disabling ATA/IDE in the kernel and having to figure out why it no longer boots :p).