@ActionRetro How about #BunsenLabs #Linux on the #T61?

Because that'll run awesome...
https://www.bunsenlabs.org/


Sadly unless your T61 has a #Core2Duo upgraded it won't run #amd64 / #64bit distros, so you won't be able to use @tails / #Tails on it...
https://tails.boum.org


Otherwise do it like @fuchsiii and upgrade the #T61 beyond reasonable specs with something like a 2TB SSD and use it as #WindowsXP or #Windows7 #retro machine...