Problems with uninstalling boot camp

Hi everyone,

I tried to install windows 7 in my Mac Boob Pro (2007) with bootcamp, but it didn't work, probably because i got the old version of mac book pro...
So I deleted the bootcamp partition (now I got just the macintosh HD), but when I turn on my mac, it stills open that black screen, saying something like this ''no bootable device -- please insert a CD and press any key''.
Because of that, when i turn on my mac i got to hold the option key to select macintosh HD and run the Mac Os sistem.

Anyone knows how do i fix that?

obs: I have Mac Os Snow Leopard 10.6.4 and bootcamp 3.0.1

(by the way, if any one knows how to install windows 7 in the old mac book pro without being with a virtual simulator, like parallels, and also without deleting the macintosh HD, it would help me a lot)

Boot into OS X and open System Preferences/Startup disk.
Select your bootable system and close the window. Should fix the problem.

Yep, I tried this yesterday and it didn't work, but now I don't know why it worked...

lol

Anyway, thank you ^^