Good PC for Kdenlive

I am about to buy a new PC ( 1-2k$ without HDDs). I´d like to optimize it for videoediting with Kdenlive. Iḿ just to use MXLinux and will continue with that distro unless you strongly propose something else. What hardware should be used? CPU, Systemdisc, RAM, Graphic board, etc ?
The standard theme i MX is not good. Is there a better XFCE theme?
Hans