Hi Rikki,
I have a 10 yr old Casio CTK-750. GM set, some nice solo sounds (for the money and time I bought it, you can't use them along with styles though) and 128 Styles.
My playing ability hasn't exactly surpassed it, but there are new toys in town that I am drooling over, you can say that I am bored with it.
I am not a musician, I just play at home for myself, usually try to learn songs that I like, always using built-in styles, never going to gig. Maybe once or twice a year, I will play along 1-2 guitars in a gathering at a friend's house, so the things that Frank describes in his (Thanks Frank!!) are more suited to a professional, than me.
So, after reading around here in the forum, it seems like OMB and a decent softsynth (HyperCanvas sounds are miles ahead of my current Casio) may do the job as needed, excet the "portability" thing.
The "new portable toy" alternative would be a Casio WK 3500, or a PSR2100/3000 if I starve some months, money is a little tight

I suspect I would need to buy OMB & Forte & HyperCanvas, can you describe what else do I need If I go the software route??
Thanks for reading my life's story, hope you have the time to help.