[Users] 32bit Linux recommendation to run Claws on an old laptop

[mi]

Claws does not seem to use up any significant resources; and for slim or scaled down linux editions, 4G Ram and something around 25G disk (without user) is still enough too.

IMHO you can run many decent GNU/Linux distros on such specs, if you deploy a rather minimalistic desktop environment. Switch to manually selecting packages (instead of full scale auto-install) in the installation process. Debian or Mint LMDE,  Arch, Gentoo, are offering such installation modes, i don't know who else. I believe Ubuntu or SuSe are not a good choice for slow hardware. If unsure try Debian, a safe bet.

Usually people say the best speed/comfort compromise for desktop is xfce4, but even more resource efficient is WindowMaker (wmaker). This is a nextstep clone (yes, Steve Jobs) though and is quite far from modern desktop standards. Anything is about configurable small tiles who can be connected like a 2D minecraft. Multiple workspaces. Fast as hell. Personally i like the minimalistic concept. (using both)

Then, you could try some tricky magic, like reducing screen resolution (xorg configuration) and drop as many background services or daemons asyou can bear. (Even syslog can be deinstalled, on a desktop machine, if anything is running fine; and you can reinstall if problems occur.)

If that 128G drive is already an SSD then that's the most cruciual speed factor anyway.
And fast internet :D

You could partition e.g. 30G System and the rest /home (plus one swap 4G if you want safe hibernate) - the split makes it's easier to exchange the OS later, if you like to compare. Or double boot 2 OS, then you can afford to screw one up :D

hth micha