I was a Tibook lover for many years and you should know my original 400ghz Tibook is STILL RUNNING, purchased in August 2001.
I replaced the top case on it as well, wanted it to be brand new
The best thing you can do for you tibook is keep the fan clean, and install the newest 250gb or 320 PATA hard drive that will actually run COOLER than older hard drives. ALso make sure you have maxed out your ram.
A stand helps and make sure the little rubber feet are in place on the TIbook. Apple told me a week after I got that first Tibook that the little feet were there to insure airflow underneath the casing.
Maxed ram and newest hard drives will take stress off the logic board.
One good thing about the DVI Tibooks is they had separate dc in boards. In case of failure you can just replace the dc in. Earlier Tibooks had the dc in built into the board, so it if failed, your whole board was dead.
Also upgrading to a new superdrive also takes stress off the machine.
Think about the upgrades this way: in case of catastrophic failure, you sell the new parts off. Easier to justify the money that way.
Also, somewhere, someone used to sell TiPaint just for the Tibooks. Good luck finding a bottle but it may save you from having to buy a new topcase.
OH CRAP just realized some NEWBIE from Iceland (Magnus Arnason) resurrected a 2 year old thread and I wasted my time on this.
Thanks noob for the time suck time warp.