If they do not have network cards, then a 'laplink' cable and software will do the trick. May types around now. Link each machine via the parra or serial ports to the newst machine. Suck up the data and organise/burn to CD.
Delete as best you can, running specialist software if needs be - i.e. commercially sensitive data.
If the machines are not needed, most town refuse areas have hardware places. Remove the hard drive and disable it with a hammer - for your security!