The 2000 I recently sold had a few articles and files from the original owner, who, back in the day was a jobbing writer for AUI.
When I told him he was happy for me to leave them on there and even have a browse through as it was all out of date stuff that he was no longer interested in.
It was a nice bit of history so I told the new owner as well.
I also picked up a libretto 50ct from its owner at a car boot sale about 3 years ago and it turned out to be a cash-point service computer!
It had loads of 'interesting' software, contact details & Passwords!
Needless to say I formatted the drive and securely disposed of the discs, passwords and associated equipment.
I eventually resold that (after playing with it for over a year), but not before I securely erased the hard disc again and re-installed windows.
I have also picked up numerous hard discs which have turned out to be jam packed with all sorts of personal and financial details.
Personally the thought of sending any system of mine to any of these 'service' centres would be the last thing I would ever do.
No hard drive has ever left my possession without having sensitive information securely erased, I don't think my sanity could take it. :-)