whats the difference btw these korg synths?
Well, the S would be your best choice of all the electribe in my opinion... The A is a bassline synth, and its limited by its own soundbank (and it can't sample). The R is a drum machine, a good one, BUT again you are limited to the drum kits included..
With the S you cna trigger any sample, drums or synths...
if i choose the es1 what else do i need to produce decent house music??
Quite frankly, if you get the ES-1 and expand its memory to 64MB, you will be fine.. later, you will probably want to get a synthesizer or a bigger sampler, but the ES1 is fun and complete enough to start getting into things.
Of course when you'll get really good at this stuff you can go for a more profesional studio setup, but for now really its a fun machine to have.
can i hook it up to mu computer and stereo?
Yes you can hook it to your computer and record your songs as WAV files, burn an audio CD or even control the ES1 from a MIDI sequencer if you feel like it.
is it really good?
I've heard great things about this machine. Go for it.
i like the idea of making my own patterns sounds and tones and samples not just using the ones on the machine, can i do that to a good extent or just averagely??
Because the machine is a sampler, you can really sample anything you want (if you make sounds on your computer you can get them and map them to build your own patches in the ES1, or even record a frying pan falling on the ground, a bottle smashed on the wall... i exagerate, but these are good examples).
so many q's hope i'm not annoying you
oh yes you're annoying

LOL joking man you can ask away as many questions as you want, this is what FutureProducers.com is all about
by the way the ES-1 is 400 US dollars not australian dollars. You may pay 500 for it though (depends).
As I said earlier, if you have more money to spend, get the Yamaha RS7000 it is a nice machine. Its basically an ES1 on steroids.