Trouble creating icons for my workspace

X7 only allows .bmp, .ico and some other gibberish. I've tried everything to create my own icons but no matter what I do they come out looking horrible. both .ico & bmp.

.ico 16px sq, 128px sq etc no good.

bmp @ 16px sq $ 300 dpi still no good. Antialias off. doesn't matter. What am I missing?