I seem to recall that AMDs are designed to handle 80,85 or 90c? depending on the model, so I wouldn't worry too much.

Remember that the room temperature is what it will balance to, and the airflow around the outside of the case is important. I have seen quite a few fancy workstations that allow very little airflow around the base unit

When you get a retail boxed AMD it will have a heatsink and some thermal compound. I don't use these..........Cooler Master make some nice heatsinks (there are other good makes) and silver thermal compound is much more effective.............just check out that the fan/heatsink is approved for your processor...............I have seen a guy fry two 1.3Ghz Durons, using an inappropriate heatsink

You might also replace the ribbon cables with the circular variety, and add fan cooled 5.25" HDD mounting bays. Modern 7200rpm drives can get very hot, and the objective is to create an airflow that moves heat out of the case. If you let stale air build up around the drives it will kill them.

Cable ties are very cheap and often ignored. Keep wiring out of the way so it doesn't impede airflow

Cheers