Make note of the fact that most the people on that thread say you need certain versions of photoshop but it seems that tool will do all the work for you as far as conversion goes so you can make use of any vx ace tilesets as if they are xp tilesets .
There are probably way more futuristic tiles for VX than XP, so I'd say your best bet is to just gather VX tiles and reformat them for XP.
If you're looking specifically for pixel art style, the DS+ resource pack in the forum store has some really great modern/futuristic tiles. Again, they're formatted for VX, but you can easily make them compatible with XP.
Every once in a while I check to see if my planned game titles are taken or trademarked. Still okay. I plan to take my time for the sake of quality, but at the same time it feels like a race against some hidden dev out there who also plans to publish or register the same title.