Lightweight distro lk 2.6 for driver development

I am planning to set up a system to learn and practise developing device drivers. For this, I am planning to buy a relatively low end used computer (something like a P2 400 MHz, but I'm not sure about the exact configuration yet), as it will be cheaper. I want to install Linux kernel version 2.6.

1. The textbook recommends downloading the kernel from kernel.org, as it says the distros can be heavily patched and divergent from the mainline. Although this can be done, I would still prefer a distro, something which is the same as or very close to the mainline lk 2.6. Please recommend some.

2. The other requirement is that this distro should be light enough to run in an older computer. I had heard that Vector Linux is good as a lightweight distro, but checking its website revealed that almost all versions use lk 2.4. The ones with lk 2.6 has higher requirements for memory, HD etc which I'm not sure this old computer will have. Any recommendations on this (which should also satisfy the first constraint)? What is the minimum configuration needed to run a lean distro with lk 2.6?

Thanks for any help.