I have the DX10 preview unchecked and anti-aliasing checked with tri-linear selected.
If I run FSX in Windowed mode, it works OK. It's only when I try to run FSX in full-screen mode (From the menu bar, select View and then Full-screen) that I hit the problems - when the "mini windows" that are supposed to appear when starting up (with a timer bar shown) or other options selected such as Flights - Navigation Log, or World - Map, and many others, will not display - when these options are selected, the main FSX view turns black (which is fine) but the relevant mini-window doesn't display. It is a display issue because the option is present in the background and responds to any key presses (if you happen to know them). This isn't practical in use and on my PC (a laptop), it's definitely preferable to run FSX in full-screen mode and this works just fine in Windows 8.1.
Phil Tosney