I've been enjoying the Impasse bike, but even though it was fairly cheap I'm worried about theft- 29-inch wheels and dual-discs would probably bring thieves whether they're cheap or expensive. So I have been looking for a dead cheap beater bike that's decent enough to survive some crap treatment, and unappealing enough to keep it from being stolen.

Yesterday night while riding I found an old mountain bike that someone tossed in the garbage on their front lawn. I picked it up and brought it back home and discovered it's a Jamis Explorer 18-speed. I can't find anything about it online, all that comes up are the new Explorer models. Anyone who knows, were they good bikes? Better than walmart crap? Sturdy and low maintenace perhaps or just garbage?

I have a U-lock+cable lock in my rucksack, doubt it would be enough for my new bike but for a beater it should do okay... right? Or are thieves stupid, desperate or crafty enough to make off even with a beater bike with the dual locks?

If anyone has some good security methods, like how to lock the bike properly, what to lock it to, etc. Also, should I keep it dirty and rusty (which irritates my OCD) or clean it up a bit, or will that increase risk of theft substantially?