...that you were so well dressed when you were here Alex or I would have charged you more money too.
Good luck with the new parts. Use lots of grease like bisbonian suggests but clean it frequently, especially if you go through a lot of sand and gravel. Use WD-40 or kerosene (lamp fuel) to clean the chain before you re-grease it and it will last ok but with more frequent adjustments.
When I was young, we didn't use O-rings chains. We used to take the chain off and put it in a bucket of used motor oil and heat it over a a camping stove until it was warm. What a mess that was.