Well a week ago I installed a 320gb hard drive and 4gb of memory into my Mac Book Pro. I managed to put everything back together and only forget to reattach the keyboard. I finished the last screw opened it up and pressed the power and nothing happened. I thought oh no what did I do and then I thought I don't remember if I connected the keyboard. So after disassembling it again, reconnecting the keyboard and then putting it all back together it work.
Today I purchased Snow Leopard and as far as I can tell the install was perfect.