In the end its up to you mate, but consider a few things ,
1) The 360 has a bigger game library at present, has more AAA rated games and has the Halo franchise
2) It is still unproven if the 360 RROD problems have been full addressed, even with a 3yr warranty for this problem only, if it fails you will still have the hassle of taking it back sending it Microsoft etc.
3) The PS3 has got some good if not great games out for it now, plenty enough to last till well into the new year when the even bigger releases are out.
4) HD-DVD/BD not an issue if you're not interested in Hi Def movies but if you want one then the 360 will cost you £99 more for the HD DVD drive were as the PS3 BD is included. Another thing to note is to check the current disk releases and see which format has the films you want to watch.
5) Xbox live is a better service currently, but you have to pay £40 a year to play online games where as the PS3 one is free. Live is more " Friendly " in a way that in game messenging and invites work but this should be sorted in the big PS3 update. If you just want to play games against your friends then PSN works great, also many Sony Franchise games EG Warhawk and RFOM have dedicated servers not just P2P.
6) Xbox 360 gets game demos normally before the PS3 or even Demos the PS3 doesnt get, also with the PS3 the EU PSN store is nowhere near as good as the US one so you have to sign up for a US account as well (not a problem though)
7) Many people think the 360 controller is great and the PS3 one nowhere near as good, in some cases it may be, but i still prefer the PS3 pad to the 360, but thats just my opinion. Also the Sixaxis doesnt have rumble, but early next year ( or this if you import like i am ) the Dual Shock 3 is out, which is a rumble enabled Sixaxis.
8) This is the big one for me, It depends on which Company games you prefer to play for example I would take GT over Forza any day. So if you have played Sony games on your PS2 then the PS3 is the only place you will be able to play them, much the same as with Microsoft Franchise games will only be on the 360. The Sony Games im talking about is things such as God of War, Ratchet and Clank, Jakk and Daxter, Gran Tourismo, Singstar, Killzone etc.
9) Not totally correct, but most 360 microsoft exclusives end up on the PC for example Gears of War, Halo, Bioshock. Im pretty sure that Halo3 and Mass Effect will both appear on the PC shortly, especially Mass Effect. So if you have a decent gaming PC it kind of negates some of the reasons to get a 360, but not all.
This is no way a comprehensive list but I hope it helps you in deciding which console. A few months back the 360 would be an easy choice to pick for some but now as the prices have dropped, more exclusive games are coming out and most multi platform games being about equal the PS3 is far easier to recommend.