Thanks Sonsey, hopefully I'll be going to Burleigh as well, I'm going to try and get a press pass.
With regards to tips the best all round lens for this type of event is probably a 70-200mm zoom, you should be able to get most of the shots you want. Having never been to Badminton before I went out on Friday and bought a x1.5 TC, I didn't use it in the end although I could have but I didn't want to keep swapping lenses due to the amount of dust. What I did find with the crowds was that most of them were doing what we did, watch one or two riders at a fence and then move onto the next one, however it was very busy and trying to get a shot when I first arrived at a fence was nigh on impossible but as soon as a rider passed that was the time to move in and bag a spot.
The light was a nightmare on Saturday, very bright and hazy as you can see from the pictures. I tend to use aperture priority for most of my equine work, I know this probably goes against the grain but it works for me, I'm usually somewhere between f/2.8 - f/5 which gives me a good shutter speed, I find that 1/400th is about fast enough but you can go slower if need be. I also use the Auto ISO feature on the D200 which can be handy at times. I also dialled in +3 or +7 EV to try and retain some detail on the horses and riders although this meant blown skies.
I noticed on the other Badminton thread that some people mentioned that there was no sense of movement which I find a bit odd if a horse is six feet in the air with all the hooves of the ground! Equestrian events like this are different to motorsports, when conveying a sense of movement with cars or bikes panning is combined with a slower shutter speed to blur the background, this is ideal for this type of photography as the subject is usually moving on one (horizontal) plane however you can't use this technique for showjumping or cross country as the horses are moving in two planes - horizontal
and vertical. Quire often they are also coming straight towards you as well so you need the higher s/s to freeze the moment.
Hope this helps and if you have any more questions just fire away!