FINAL SCORE:
Rikk & his X-kilt: 0
Walmart fabric of unknown thread content: 1

I spent a good two hours playing around tonight, tried everything possible. Upper and lower tensions, new needle, different size needle, stitch length, foot pressure.....no dice. Pucker, pucker, pucker. So I had some fabric of a similar weight that I'd used to make some flashes with. Folded it over, set all the settings back to "normal" ran a line of stitches down each side of a faux box pleat. Perfectly straight. (Insert lots of vulgarity and profanity here!)

I'm going to venture up to Joann's tomorrow night and buy something decent to sew start over on. At least I'll be a bit more experienced at the calculations and the layout. Once I'm back to the sewing part, I'll pick back up with this thread.

Be warned, before you take the time to layout and start sewing your X-kilt out of an unknown, cheap fabric, buy a sample of the fabric and try sewing it first. It may be like my "EX"-kilt fabric and have a mind of it's own.