Two months ago I thought the same you did :
I bought the 10gig version, and added a 48gig IBM drive to it. It's not really that hard, just be a little careful when you're doing it. The FAQ Tony has written on it and that you can find on riocar.org and here in the FAQ section is really good and all you need to know really.

Last week the car2.harddisk builder utility got updated and should show no more problems with Rioplayers (or Empeg MK2a as most call them here) anymore. I had to do it the hard way since this utility didn't funtion correctly then with MK2a's, but you won't have that problem anymore

I had my player for a week before I did the upgrade. So yes, I voided the warranty. But the Empeg guys are real cool about that. See, I had forgotten that the harddisk cable is glued to the harddisk (to prevent it from falling off during transport), and I damaged the cable somwhat by pulling it too hard without removing the glue first. I contacted Empeg and they've sent me a new cable free of charge, despite me voiding the warranty! How cool is that?

I suppose if you don't do anything really stupid like breaking off a cap because of rude behaviour or opening up the player whilst the unit is playing and by that short-circuiting the thing, they will still help you if you're in trouble.

This is also one of the BIG reasons which made me decide to buy an Empeg. See, here the original designers of the product or somebody else from the company actually TALK to their customers and try to help them in every way they can. SSI could learn a thing or two from these guys!
When you've asked the Empeg guys something and they answer with "sorry, can't help you there", you can be absolutely sure they've done anything in their power to help you but it just can't be done.

So so yourself a favour : buy that Rio!