No it isn't.
If all you want it for is playing games online, then the 360 is streets ahead. It has better exclusive games, the controller is nicer, the online interface is better, it's cheaper, you get a headset as standard so online communication is better and it's just generally a better playing experience.
I know it's �40 a year (you can get it cheaper than that through Ebay), but the experience is better. There's a lot less little turds playing as the fee stops them playing. Games get patched much more quickly to stop glitches which does not happen with the PS3 - I know glitches in COD 5 that still aren't fixed allowing cheaters to win each time.
I have both, and the PS3 gets used for the exclusives and nothign else. If a game is availble on both formats I will always buy it on the 360. It's a more rounded machine. The reduced price over the PS3 means you technically get the first 2 or 3 years of Xbox Live for free anyway so it becomes a moot point