360.

buy Xbox360 man ... online+FPS, this console is for you

You like shooters, online, and the occasional RPG. The Xbox 360 sounds like your style.

Of course, if you're more into strategy RPGs like Fire Emblem or Advance Wars, handhelds are for you.

 Montana has an interesting idea, have you considered a handheld? They're much cheaper, and you can spend the remainder of your cash upgrading your PC--the far superior FPS platform in every way.

Yeah the Xbox 360 looks like your thing, and pc's are also good for fps, i got two 8800GTX's in SLI and it blows away everything.

But if you want a console for shooting xbox 360 is your best bet... also now that Atlus and Microsoft are now freinds you can expect a few decent rpg titles for the 360.

 I think all the new Xbox 360's have a new chipset that eliminates the threat for a red ring but don't quote me on that.

http://images.google.co.uk/imgres?imgurl=http://content.answers.com/main/content/wp/en/3/3b/Videopac-pete-screen-800px.jpg&imgrefurl=http://www.answers.com/topic/videopac-pete-screen-800px-jpg&h=695&w=800&sz=53&hl=en&start=3&tbnid=aymqKUC2UO3QWM:&tbnh=124&tbnw=143&prev=/images%3Fq%3Dphillips%2Bvideopac%26gbv%3D2%26svnum%3D10%26hl%3Den%26sa%3DG

Get a phillips videopac - this was my first ever console

You already have the best FPS system, and PC games are cheaper too.

You will be fine with either a 360 or a PS3. Look at the current and upcoming games and see which system has more games you are interested in. If your friends play a console, you might want to get the same one, so you can play online with them. With all other things being even, you might want to go 360 for a larger game selection.

That pretty much puts the 360 as your option, then...  There are so many good shooters on the 360 at the moment that you will be busy for quite a while to come...  BUT, keep in mind that a lot of the great shooters on the 360 are also on your PC...

There are some decent RPGs on the 360 as well with Mass Effect just coming out and Lost Odyssey on the near-term horizon.

In second place, you have some shooters on the PS3 as well but not nearly as many at the moment.

Lastly, the Wii... Great console, but if you are a shooter fan, there aren't that many.

If you do get a 360, get the elite so you have the big hard drive and check the manufactured date.  Look for one made October or later to be sure you get the latest hardware.  The 120 gig hard drive will come in handy...  If you can't swing the dough, the Pro is still a good deal, but you will eat up the hard drive pretty quick if you like to download demos and such. 

 If your friend has a console, just buy a controller and play on the same screen :D

PC upgrades are the answer you're looking for. You know you want to. You need to. 

There's a big sad eyed puppy wondering why you're thinking about abandoning him. His name is PC, and he's a slice of deep fried golden l33t. He's sad, he's CRYing! Don't make the puppy CRY.

http://www.youtube.com/watch?v=pPi0AhQgrDs

There's only 1 way to save that puppy, and it's not on a console.

If your option does not include getting a PC, or at least upgrading your PC (you can get a great video card as cAPSLOC mentioned), then 360 obviously. As for which model... I need to own one to give an answer. Frankly, I find the PC to be far superior to any console in FPS, it's cheaper both in terms of online fees, selection, and game pricing*.

P.S. You need to pay for the 360 online multiplayer service though, so I am not sure if you need to consider that into your budget

P.P.S. In addition, since you have a good PC already, and I assume you play FPS on that, it'll take some getting use to the 360 controller. (I personally prefer mouse over dual analog, but that's just me)

P.P.P.S. Stick with your PC if all you want to play is FPS game, most of the FPS games on 360 will eventually end up PC anyway, it's only a matter of time.

* purely speaking in terms of NA, since it costs about $50 for a PC and Wii game, and $60 for a 360 and PS3 game.