MacBook :: Blinking Screen And Not Booting

I've had this 2.0 Ghz 1gb ram Macbook since September 2007 and this was the first time I've ever had any problemas with it. So let me start from the beginning.

It all started this year. One day I picked up my Macbook and turned it on and I noticed that the screen was blinking quite a lot... then it started to get worse to a point I got really worried and it started to annoy me. Sometimes I'd boot it and Leopard would be changing my wallpaper every second (it's supposed to change my wallpaper everyday according to what I've setup in system preferences). While blinking the colors would get messed up and when I closed the Macbook and let it on, sleeping, I'd open it and it would be on the blue screen as if I had just turned it on.

It's worth mentioning that I was running a version of Leopard I downloaded from a torrent and had installed it from an external hard drive. So I thought I should try to format the machine, erasing everything and installing a new and original version of Tiger. Once I installed AND got all updates installed as well it was running perfectly. The blinking had gone away.

Yesterday I installed some new updates, booted and used it fine. Today I turned it on and it won't go past the blue screen and the apple logo won't show up as well. My Macbook just won't boot... I've tried booting on safe mode, booting with the tiger dvd on, i've tried resetting the pram and everything else I could do. The apple logo won't seem to appear and the machine won't boot.

First the blinking screen and now it won't boot.

Any other suggestions besides taking it to a support store? It's worth mentioning as well that I live in Brazil and support to Apple computers isn't as great and cheap as it is in the US. I've had this Macbook for less than 1 and a half year.