I hear in magazines that Games Workshop paints are good quality - but the ones I have (Space Wolves Gray and Skull White, in the old bottles) tend to bead when I thin them with water Is there anything I can do to fix the problem?

how much water are you putting in them? About a few drops I think is all thats needed.
Also are you thinning them for brush painting or a Airbrush?

For brush-painting (the only painting I'm going to be doing until I get a compressor.... ) I put in about a full eyedropper's worth of water into about a tablespoon's worth of paint - just enough to get it to the consistenct of 2% milk. The irritating thing is, it beads when its thin enough to paint evenly - the only way I've found to get it on without beading is to use the stuff thick and straight from the bottle - making it almost impossible to brush on properly.

have you tried mixing it with some tamiya thinners or window cleaner for cars this may work

Yes, I totaly agree with mikali, however, you don't actually have to go out and purchase tamiya thinners, all it is is thinned rubbing alcohol, thinned with water,of course. I also have alot of mthe old paints, given to me by my uncle,who, I may add is an excellent figure painter.

Games workshop paints are getting more and more comment in this hobby. Several articles over the last few months, have included references to games workshop colours for finishing. Their gun bolt metal for instance seems to be very popular. Most of the times they seem to be used for small touches and for metals. havent heard anything about large surfaces. They have a range of very useful inks as well. I have read somewhere that someone has used their flesh colours very effectively as well and the 3 or 4 colours work really well together for shading and highlighting. Have never used them my self though. But have read enough to warrant a try and they will be something I will be looking into!

Their rattle can primers are excellant to use also. They go on very thin and shrink so you lose no detail at all. The only down fall I see with them is that they can be pricey. $9 a can, but a can last me forever so I splurge every once in a while.
Paul