For the timing belt, I think most people here use:
Continental
and some people use:
Gates
Gate is actually the preferred choice for the newer TDIs, but I'm pretty sure Continental is the most common for the older cars. They go by several names: Conti, Contitech, CRP, etc. I think autohausaz.com carries that belt.
For water pumps, there are several brands that all work fine. Some people won't put anything but a cast iron impeller on thier cars (like the factory pump). For that style, you'd need to buy:
Meyle
Meyle is the OEM aftermarket supplier. Some parts are still made in Germany, but some are made in Turkey, India, China, etc. With them, there's no guarantee.
Sometimes GRAF (italitan company) will have the cast impeller on it, but sometimes it won't. At least their parts are usually good quality (not the smoothest casting work, but quality bearings). I usually go with them, or....
GMB
GMB is a Japaneese manufacturer (yeah, I know). Their impellers are always stamped steel, but the quality is good nonetheless.
My dad is actually a Foreign car parts retailer, and GMB and Graf are what he sells more than anything. Most of that has to do with the fact that they are slightly cheaper, but at least you can be assured of the country of manufacture. With Meyle, you're only really guaranteed that the part will have a cast impeller (and who knows these days). I've bought many Meyle parts, and some of the same parts were made in vastly different countries, even when I bought the parts a few months apart.