How do you tell if a geared bike would make a good fixie?

[Jay]

I have an old geared bike and i really want a fixie, how could i tell if the frame was reusable for a fixie?

 

[Bob A]

If the rear drop outs are horizontal it will make a great fixed gear bike. The hardest part in converting a bike to fixed gear is being able to adjust the chain tension.

http://www.google.com/#hl=en&source=hp&q=horizontal+dropouts&aq=1&aqi=g10&oq=horizontal+drop&fp=baa94940edcea411