Problems to update

I'm totally newbie in MAC, and install a SNOW LEOPARD in my DELL D630.

Two days take to understand principals of MAC, I have experience in Linux, BSD, Free-BSD, Windows, but never MAC.

I install Snow Leopard with EFI:

1. First boot with EFI
2. Install Snow Leopard.
3. execute EFI post install to boot from my HD and fine.
4. Install another "ketx" and all fine.

My problem it's with APPLE UPDATE, suppose this it's not a problem, but don't work, if I try execute "Software Update" they never found new option, I have installed 10.6, and know have new version, try download directly MacOSXUpdCombo10.6.3v1.1.dmg , but this indicate "This volume does not meet requirements for this update", I try version 10.6.1, 10.6.2 or new version of SAFARI, because ITUNES STORE need new version to work, and nothing, all pkg download from apple indicate same problem.

I suspect problem with BIOS - EFI, and read about, but if I see in "About this mac" in "more info" they indicate

model name: MacBook
Model Identifier: MacBook3,1

I suppose with this information EFI simulation it's fine, but nothing happing with update.

I intall many other programs, all fine, but updates from apple it's impossible.

Any idea what happen?

Thank's...