To answer your questions:
The games I've played online, I found it really good. You have all the common functions you know from pc gaming, like voice chat, text messaging, etc. Of course you will find some raging teenagers now and then...but my experience till now has been very positive. And you have that kind of species everywhere. If they suck, you can mute them. Playstation Store gets updated every week with new content, like DLC, demos or smaller games (which tend to be very original).
There are really good games to play online. The predominant genre is of course FPS, you have tons of those. I've been playing Killzone2 lately and it's been a blast! Really some nice action going on online, love it. Then I've also been playing StreetFighter IV, which is also a very good game, and it's nice to play online against friends for example. If you have no friends available, you'll always find someone to play against. There are a lot of really good players you can challenge. I've also played Metal Gear Online for a while, which was kinda nice too. That's how far my online experience goes till now. But there are plenty of really good games on PS3 to play, and this year the line-up is really impressive.
Yes, I also use the PS3 for media. Once you've watched a blu-ray on it, you'll always end up buying more and more. I love the blu-ray experience. You can also watch photos on your console, or play music. Overall it is very easy to use. The operationg system of the PS3 is really well made, you'll find everything you need right away. Watching movies etc, with the controler is simple, no need to buy the remote control in my opinion.
The only downside is the price of the PS3 I'd say, as it's the most expensive console atm. Games are not cheap either (60-70€), although I've been buying a lot from amazon.co.uk recently as things there are REALLY cheap compared to what you get here. I've bought Killzone2 at its release for lets say 30€ while here in the continent it costs double that price! But still there's some money to invest. Online gaming though is free on the PS3 (which is not the case on the XBox).
But yeah, Bucky got a point, you should consider that as well. I mean, you seem to have some good PC equipment, would be a shame not to use it.
