Re: Timing Belt (05S80Driver)
For '05 there are two turbo models, the 2.5T and the T6. The 2.5T is due for timing belt replacement at 120k miles and the T6 at 105k miles.
It is a fairly involved job where precision is definitely key. The worst that could happen is that during timing belt installation both camshafts and the crankshaft get out of time, bending the valves and trashing the cylinder head when the engine is first started. A skilled DIYer can do the job nonetheless and save big fat coin compared to what a dealer or other mechanic would charge for labor.
Since the water pump is driven by the timing belt, it does makes sense to replace it at the same time.
I recommend getting a copy of the latest 2005A version of VADIS--check eBay--which outlines in detail all the service information that you'd need.