couple of quick questions, but first a little background. My old Trek 400 is sitting in the shed, not being riden at all. I'm looking for a project and I thought...why not convert the Trek to SS? I've never done such a conversion, but I'm not afraid to give it a shot.

I know there are simple ways to convert a mulit-speed to a single-speed by reusing some of the original parts, but I'm really looking for something to do some tinkering on. I also would like to keep the original setup intact in case I want to go back to multi setup.

First, how do I determine the best gearing for me? Take the Trek out as is and find a comfortable gear set up and start with that?

Any hints on parts that would work on this frame, but not kill me financially? I have to keep this on the cheap or the wife will have a fit. (I found a cheap conversion kit at Nashbar which I guess would be a starting point, then if I like riding SS, I could upgrade later).

I've been looking at parts at Harris Cyclery also, but don't want to start ordering parts until I know the basics of converting a bike to SS.