Some games are only for PS3 and most of the best games
only come out in Console. So even I upgrade the pc, I won't
be able to play every games,right ?

the wont be able to play EVERY game unless you do both. The ps3 is still new though, so you can be sure you are getting a couple good years of play out of it without upgrading, unlike the PC, which pretty much needs an upgrade every year or so.

depends on the person but good question

Well really with PC upgrades you can alwaysget an emulator and play ANY console game on your PC.

So I would definately go with a PC.

Consoles have really let me down recently.

What?

the ps3 beacause it has great exclusive titles and will keep up with new technology until aaround the year 2015

I would go with the PS3, nothing to upgrade unlike a PC, where you would have to upgrade it every year or so to be able to play the latest games.

Get a PS3. Simple. No need to explain why. But if you want me too...here you go.
-Better graphics
-Easy controls
-Exclusive games
-Faster loading
-Free online play

There you go

true, but regardless of this fact computer upgrade would be so much better. Because of graphics, the ability to manipulate the games and really cool games that haven't come out in console because only a computer can handle them (for example crysis, spore, crysis 2, world of warcraft) It's really depends only how much you're upgrading your system too. If I had the money and time I would upgrade my computer. But for now I have to stick with my ps3.
But seriously PS3 DOES NOT HAVE BETTER GRAPHICS THAN A PC. TRUST ME ON THIS!

actually you can play any games on the pc
i mean any console game
but for that you need a computer mechanic or someone who knows about pc
and pc graphics are great at most games
i mean if you get a good graphics card like Nvidia 8800
see it depends on you
but if i was in your place i would definitely upgrade pc
have fun
hope i helped