SDH, has offered sound advice i recomend you consider it the z400's have very good support and the hardware is well supported
on a side note to SDH,.. i have sitting in the corner HP xw8000/6200/6400/6600 systems in bootable condition
and a win 10 upgrade was tried on each of them as someone in "IT" was currious about OS support, only the 6400/6600 systems were upgradeable the older systems with 604 cpu's would not do a win 10 or win 8.1 upgrade due to missing cpu instructions