Online Functionality Xbox360
The Xbox360 has the most extensive online functionality amongst the three, thanks to the Xbox Live Network. Microsoft has done a great job with Xbox Live, making it really easy to find/add friends, invite them to games, keep track of what games they’re playing and how much so (via the achievement system). You can also buy a ton of arcade games on the Xbox Live network, and download demos, themes for your dashboard, game trailers and movie trailers.
The catch here is that to do most of that stuff or to even play online, you need a Gold Membership, which requires you to shell out a good chunk of cash. This membership costs Rs 350 for a month, Rs 880 for 3 months, and Rs 2,200 for a year. To make things worse, if you wish to buy something as basic as an avatar or a theme, Microsoft charges you! In short, while the Xbox Live service is really good, it should have been made available free for Xbox360 owners.
PlayStation 3
The PlayStation Network isn’t as sophisticated and doesn’t have the plethora of features Xbox Live has (yet), but it gains the upper hand in a couple of key areas. For one, the service is free! Secondly, there’s less lag when you play online since the PlayStation Network hosts dedicated servers for most games, making them far more stable than the player-hosted servers Xbox Live uses. Also, Sony doesn’t charge for stuff like themes and avatars.
Wii
Apart from the free online play available on the Wii, the online segment is broken up into Channels (which includes a News Channel, a Voting Channel and Virtual Console, among others). Virtual Console is a lot like the Xbox Live Arcade, where people can buy games present on all of Nintendo’s old consoles.
Stability
Xbox360
The failure rate of the Xbox360 is the highest I’ve seen to date. The console is ridden with hardware failures, and this is denoted by three flashing red lights on your console, nicknamed the Red Ring of Death (RRoD). Microsoft has extended the warranty just for this issue, so if you console RRoDs within 3 years of purchase, they’ll replace it. If it weren’t for the great library of games, there's no reason to even consider this console.
PlayStation 3
Unlike the Xbox360, the PlayStation 3 is one of the most sturdy pieces of hardware I’ve seen in a while. The earlier 60GB version had a drive issue, which was quickly rectified in later SKUs. So far, there are no complains about the 40GB version.
Wii
There are no major issues with the Wii as such, but modding any console can cause a whole lot of issues, since you’ve got to open it physically before installing the chip.
hmmm.. come to the point dude, my pick is ps3 b,cause mgs4 the best ever exclusive out there n the wii is just a gimmick u just hav to stick wit a short guy jumping around galaxies n stuckin toilet cleaners in rabbit heads :D n only reson to buy a 360 is gears n upcoming gears2 n live consist of stupid lag n that is not supposed to be next gen way of multiplayer gaming were as ps3 completly lag free so no bullet lag so buyers please buy ps3 atleast for mgs4. 
