i started playing the piano about a year ago and i love it. I'm playing on a cheap, basic Roland at the moment. I'd like to progress and i'm looking for the best sound i can buy. I currently live in a flat so size and the option of headphone usage leads me to the option of a digital piano. I have been looking around on various web sites and have been very taken to the Yamaha clp 170. would anyone consider this to be a sound investment?

No digital piano should be considered an investment (in the sense that you can get you money back as the piano becomes older). For that matter a typical acoustic is not an investment (you will never be able to get all your money back, you will lose money). It's like a new car, as soon as you drive it off the lot you have lost money.

As far as how well it will keep its value I can't say (don't know). However, given the current market it will hold some value for a while (until technology outdates it).

If you want to know if an upgrade would be a good idea, then I think it likely would be.

BTW, what Roland model do you currently own? (your answer could drastically change future responses)

I have a Yamaha Clavinova CLP175. I think the only difference between 170 and 175 is how it looks. (the 175 is in a 4ft grand case polished ebony) But I think the specs for both models are almost identical. I also have an older clavinova clp550 that is 13 yrs old. The advancements that technology has made is incredible in the clavinovas. The sound and speaker system is awesome on the 175 and the touch has been greatly improved. Mine has the graded keyboard with wooden keys. It's very nice. I am a piano purist I guess you'd say. I will always prefer a real acustical piano. But I can't afford a 6ft grand, nor do I have the space for one. (IMO baby grands are a waste of money, they have such a shallow sound.) So Clavinovas are the next best thing. And there are the added benifits of not having to tune them, use headphones, different voices, record etc...
I think the CLP170 is an excellent choice and the top of the line for clavinovas.

(yikes, where is the spell check....I'm a horrible speller!sorry)

thanks for your reply! i own a Roland Em 15, it doesn't sound like a real piano to me nor does it feel like a real piano. I've heard great things about the Yamaha clp170, and for me i like to buy the best you can to get the best out of playing. But i hear that the roland hp series are equally as good. I know that it's obviously a matter of which you prefer the sound and feel of. I am however drawn to the yamaha.