The Dell Workstation from 2008 [1] could run and probably will get loaded, eventually, with Windows 10. Currently, it's got XP Professional x64, Windows 8.1, Ubuntu Studio 15.04, and CentOS 6 and FreeDOS available at GRUB time...boots to Ubuntu by default. There's a Windows 7 VM, too just for grins. The Thinkpad GRUBs into Ubuntu 15.04 with Windows 7 as an option. It will also almost certainly get a Windows 10 upgrade over the next year, too.

[1]: To clarify, that's when I bought it. The model with Harpertown CPU's, etc. was available in Q4 2007.