Alot of good perspectives and advice given. My evolution as a commuter/utility cyclist has taken me to the point where I use a 2 bike system. The 'mule' is a fully tricked out, multi-geared cyclo-cross bike w/rack, panniers, full coverage fenders, lights, etc. Mondays I haul a weeks worth of clothing and food to work with it. The rest of the week I use a fg conversion w/a seatpost rack/trunk bag combo set up as a commuter. It's much lighter than the other bike. Each day I bring my work clothing/food containers home.

A few years ago the fg conversion was a ss. Rode it for a year and bought a cheap fg wheelset. Fell in love w/riding fixed my very first ride. The post suggesting 42x17 as a good starting point for gearing is a good one. I started w/46x16 which is a little high for urban riding, but as I live rural it made more sense to me to gear a little higher. Currently, my fg has 48x16 gearing. The perfect combination for this terrain as it allows me a low enough gear to climb most of the hills in this area w/o resorting to switchbacks and a high enough combo to maintain a sane cadence on the decends.

Find a ss that suits your fancy and buy it. You wont be sorry.