go ahead and buy yourself a suit, shirt, and tie. (you can even skip the shirt if you have any polo-type shirts).
use your boots, the tony lamas are classy. personally, i think wearing the jeans would be fine too.
so, come monday, slip on your jeans, boots, shirt, tie and go to work w/ a smile.
being that this is your only suit, i'd recommend splurging and getting a really nice one
sh!t. just realized you don't even need to war a tie- so go ahead and skip it. the jeans and jacket will look nice by themselves.