Thanks for all the input
I possibly should've mentioned in the op that my aim is to try and capture some insects in flight and 1/200 doesn't seem to be cutting it when it comes to be freezing the wings. My train of thought was therefore that I needed something that let me take the shutter speed up quite a bit further. If anyone has any further input on this I'd be really interested to hear
Ooops - crossed posts!
Technically, that's easy. But actually doing it well is a different thing altogether. Stephen Dalton is the master - check this out
http://www.stephendalton.co.uk/gallery_87323.html
If you switch almost any hot-shoe flash to manual, you get very short flash durations, down to about 1/50,000sec. Around 1/16th power you'll get roughly 1/16,000sec with something like a Canon 580 which should be enough to freeze larger insect's wings.
And because you're shooting very close, there's still enough power
You have to shoot in darkness to get around the x-sync problem, and light the whole scene with flash. Lots of difficult timing and focus issues, using laser and IR trips etc, but that's how it's done.
Have a go with 'open flash' technique and you'll get something. Work forward from that, but don't expect an easy ride
Edit: you don't need to go open-flash to get a feel for the issues invloved. Set the flash on manual with a lowish power setting, shutter speed 1/200sec, adjust the exposure with f/number and ISO, and make sure the subject is against a dark background. Keep the ambient light level low.
You'll still get some ghosting and ambient blur but the flash will freeze the movement and that will show up clearly enough against a dark background.