It probably depends a lot on your planned usage and what kind of user you are (Enduser/Consumer; Professional; Developper/Hacker) and how much time you want to invest to add additional features.

PC with Microsoft Windows: The largest software ecosystem in the world. Very easy to start developing your own software, integrate tons of hardware etc.
N810: An internet tablet. Primarely a very good and pocketable websurfing and internet communication platform. Secondarely added-value through some additional software on a consumer level. Potentially lots of additional software through porting of existing Linux applications, but factually only available to very technical people due to high barrier of entry / advanced tinkering necessities.

On a PC you can do "everything, no limits".
On a N810, there are some things that can be done very well, mainly based around the "Internet Tablet" usage (because this is what is was meant to be in the first place and what it was built for in an enduser/consumer perspective :-)