Theres a review of the Korg in computer music along with some of its rivals and they only give it an average review: http://www.computermusic.co.uk/reviews/h2hmidikey2/2.asp It all depends what you want to do I guess, do you want to use it as a standalone synth or a midi controller or both? I don't have a great knowledge of hardware synths myself though, I think softsynths are the way to go, but some people still like their hardware.

Flagman I have the Korg X5D and I love it - it's not the most amazing keyboard, and it's not half as flashy as some of the stuff you can get now, but it has some great sounds, it's pretty user friendly (although the manual is a nightmare, I was lucky to buy it from someone I knew that gave me a crash course)- I think it's a good gigging keyboard - it's dead sturdy and it's pretty good as a midi controller - I've used it with an atari and there are some good sounds on it as far as drum sounds etc go. I've no idea what the Yamaha SO3 is like to compare it with though. I think the Korg is maybe a bit outdated now, but not a bad buy if you got one at a decent price.

Cheers. I pretty much want to use it as a stand alone.