Re: AS/400 "still kicking". I've always liked the AS/400, as well as the HP 3000.
Although not being made any more, the HP 3000 (er, "HP e3000") is still running in thousands of sites. Stromasys has an emulator for it, so it might outlast the original PA-RISC hardware :)
We have one customer who has over 2,000 sessions logged into their HP 3000 every day ...
not bad for 16 year old hardware!