I just bought Roller Coaster Tycoon and I was trying to install it and when i PUT the DISK in and it said it was starting winzip...it came to the end of the download bar thingy, and then a error message came up saying that "You MUST uninstall your original roller coaster tycoon before you install roller coaster tycoon deluxe. I went throught every single comp. file for like 4 hours...literally! looking for any and all files relating to a previous R.C.T. demo that i had...and i deleted EVERYTHING! Now i keep putting in the disk again and the same message keeps popping up! I'm sooooo~> frusterated! please help quick!!!! :-/Did you delte the demo or uninstall it?
If you deleted it, you should re-install the demo then uninstall it with it's own uninstaller or with windows add/remove programs.
If you uninstalled it, first check at the GAME's website for any hints and if all else fails try searching your registry for any and all traces of the game.You should use a registry scanner to remove faultry registry entries.

Also inspect the retail box of ROLLERCOASTER Tycoon carefully to see if you indeed require the full version before you can install Deluxe.