OS X :: "Cannot Install Mac Os X On This Computer" Message Pops Up When Trying To Install?

I purchased a Macbook pro with a damaged screen for very cheap from the IT guy at my work. When I got the computer all of his information was all over it. I don't have much prior experience with a Mac, I've used a PC my whole life, but I'm interested in video production and editing and I love the Final Cut Pro interface so I've wanted a Mac for a long time. I have the Macbook hooked up to an external monitor and external keyboard and mightymouse.

I decided to get rid of all of his junk so I put the OS X disk in the drive that he gave me and it came to a screen asking me to select a langauge, I selected english and then the message came up "cannot install mac os x on this computer". It then gave me the option to click "ok" or "restart"... I clicked OK and it took me to the OS X disk utilities. I used the drive utility to (atleast I think) wipe the drive, because I figured that was the reason. I wiped the drive using the "Mac os external journaled" setting and about an hour later it finished. I rebooted the computer and the same thing happen, selected langauge and got the same "cannot be installed" message.

I read somewhere tha it could be the after market RAM in the computer. I opened it up and it does look like different RAM has replaced the original 2gigs that were in there bringing it up to four. I don't know if theres a way around this, or even what brand the original RAM would have been. The brand name on the RAM in it now starts with an "A", but I'm an idiot and can't remember the full name.At this point I'm just stuck and was wondering if anyone had any ideas.Please pardon my "noob" status with MAC's - I'm not one of those PC users that hates Mac users, I'm "pro choice" when it comes to computing.