I haven't owned a desktop in about 8 years, so I can't recommend a specific machine. But I can definitely say that you should consider some machines that don't

I haven't owned a desktop in about 8 years, so I can't recommend a specific machine. But I can definitely say that you should consider some machines that don't have linux pre-installed. That said, you do want to order a machine, or parts, that play nice with linux.