Xbox Live is a much better service than the PSN, you get what you pay for and all that. I don't mind paying the £40 a year because it's the price of one game and look what you get, you get unlimited online gaming, immediate demo downloads (silver members have to wait), movie downloads, messaging, private chat with friends who aren't playing the same game as you, a proper unified friends system so you can invite your friends to your games, arcade games, wallpaper and theme downloads...
The PSN is free for a reason. It's kind of laggy at times and seems awfully hacked together, none of its features are standard between games and it lacks simple things like in-game messaging or game invites, stuff which has been standard on the 360 since launch. That said, they do say the arcade games available for PS3 are better than the 360s ones because Sony actually have some kind of quality control.
I will probably buy a PS3 but, to be honest, half its library right now consists of dodgy ports from the 360.
Okay I just want to point out a few things.
you get unlimited online gaming (PS3 also does this but its free)
immediate demo downloads (You get this with the PS3 for free no waiting)
movie downloads (You can't download full length movie's yet so thats a +1 360)
messaging (Yep PS3 has that too)
private chat with friends who aren't playing the same game as you (I guess I don't see the point of this unless you have a keyboard hooked up but the PS3 doesn't do this)
proper unified friends system so you can invite your friends to your games (Whats your definition of proper because the PS3 does do game invites, who cares if the way each game is done is different)
arcade games Yes as well as classic PS1 games
wallpaper and theme downloads... (Yes the PS3 has those as well)
Seems like your paying for the ability to chat with people through the 360 while playing a different game and a unified friend invite system.
Generally when I want to get a game together with my friends I just pick up the phone or see who's online and ask them if they want to play.
Now what you do get with the PS3 that you don't get with the 360.
Integrated Wifi no addon needed
A fully upgradeable hardrive that does not need to be a special drive from Microsoft plus it doesn't void your warranty. Also some games auto install to the hard drive for faster load times. This option is not available on 360's since some models don't have a hard drive.
A 2.0 Blu Ray player to watch the latest movies with download able content. Not to mention a huge amount of extra space to put lots of extras into the games
Si Axis controller support
Does the 360 do webcams? I'm guessing so but I don't know for sure.
Full blue tooth support for mouses and keyboards without the need of a USB dongle.
Intergrate and stream all your Music, Videos, Pictures through the PS3 creating a media center.