I am a complete noob when it comes to macs so you may need to explain things in detail. i just finished installing 10.6.4 on my Alienware m15x and next to nothing worked from the beginning. the keyboard worked and a usb mouse worked. but suddenly after a couple restarts my keyboard has stopped working and i can't do anything without that keyboard. all i have is the mouse lol. so if someone can help me get it working again i might be able to figure out everything else. thanks

p.s. things that work at the moment
mouse
dvd drive
usb

things that don't work
no internet
no keyboard
no touchpad
can't change display settings
no audio
there are probably more

You could try to install PS2 kext/driver for your kb/mouse again.