Installer changes.

Ok this is my situation:

I have a program that I am distributing, (which by the way is being downloaded like hot cakes, and I need more bandwidth). But anyways for it to be installed (the downloaded program which installs the whole thing), I want to entirely uninstall it first (to get rid of some dlls which are now not needed). I am using this EXTREMELY bad (good for begginers like I WAS) software called clickteam install creator to pack it into an EXE installer. I can't find the option to get rid of old files before install (it just overwrites). Now because of this I want to swith to NSIS (least overhead and I can make it so that it can check if the system will be ok for downloading and will give me more control). How would I go about doing this in the fasion that when this installer finishes, the previous installation is deleted in the Add/Remove programs list in windows, and then the installation is installed with the New NSIS (effectively updating it). I want it to be seamless.

I believe I have to have a registry update key to provide or something. Anyways I'm just starting with NSIS (and don't know a clue about it) and the old program just did everythign for you (so I'm clueless). I'm posting this here because I need immediate help (my program is freeware: the program is on download.com and I don't want to spend like $200 bucks for one day updating, so I have to wait 15 days for it to be done. Because of this I need to come up with an update (it's ready, I just need to make an installer) really soon. My host made me pay 120 extra because of bandwidth (I've tried to keep it small, but it still gets 300+ downloads a day and it's a 1.6mB file packed with this previous installer.

THANKS ALOT for your time and help and reading that huge post and my rambling. It's greatly appreciated. :afrog:

You can't just delete files that are installed if they are system files or other files that are used by other apps. If you are the only one that uses a file it should be automatically uninstalled and deleted.

Inno Setup will do those sorts of things for you also but you will still need to use the correct flags for it to happen and the same rules will still apply.

Moved.