Joking aside though, it's quite a tough decision. The 360 has a broad games library but this year there are going to be a lot of good PS3 games coming out.
Even though PSN is free, I personally prefer Xbox Live due to the fact that it's easier to use and is just a better service in general.
We all know that the PS3 is a more powerful machine than the 360 and so will have better looking games and what not, but to be honest I don't care about graphics.
And of course, we all know about the RRoD, but the percentage of 360s that get the Red Ring has gone down by quite a bit.
And of course, price wise the 360 is definitely the cheapest, even cheaper than the Wii.
Honestly, it's a tough choice. If you haven't got that much to spend, go for a 360.
If you're willing to save up and wait, then it maybe best to get a PS3.
In the end though, either one is fine, as long as you get to play the games, who cares what system it's on.