hidden files

I have downloaded certain programmes,but when I trash or try to remove them they seem to leave traces of themselves behind,xbmc being one such programme,they do not come with an uninstalling package,is there a simple way to locate their hidden folders so they can be deleted completely, I have tried searching in library but to be honest there are to many folders to go through,also it's quite scary as I don't want to delete something really important by accident,finder does not locate these folders for what ever reason,is there a place I can go to where they are all directed to,PLEASE ANY HELP will be most appreciated THANKS.

What do you mean by "they seem to"?

For apps that are installed and uninstalled via drag and drop, there is nothing that most users need to do other than drag and drop the app into the trash.

What is left behind are typically preference files that are so small as to be of no consequence with drive sizes today and can be safely ignored.
There is no registry in OS X, these files do not affect your boot times, application load times nor anything else.

As an example - Haven't installed XBMC on this particular machine, but I do have Plex. A drag and drop to the trash would leave a 45 MB folder and a 4 KB file. Unless you're someone that is installing and uninstalling just a boatload of apps - there really is no reason to even concern yourself with what is left behind.

For the OCD folks out there to remove them, you would:
open Finder - then on the menu bar select 'Go'
while you have 'Go' selected, press the 'option' key and you'll note the 'Library' folder appears
select the Library folder
then look in two folders - 'Application Support' and 'Preferences'

If you install and uninstall a boatload of apps, then you should get a tool for the job and there are several good ones out there.
AppCleaner is free.
I use an app called WhatSize (multiple function app and worth the price of admission)

edit: moved thread to more appropriate forum

I've read elsewhere that AppCleaner and other similar "3rd party" uninstallers don't always do a complete job. They might get most, but not always all associated files buried in the System folder.

Thanks so much, my problem was when i reinstalled certain programmes, they would come back with my old preferences still in place, when i wanted a clean board to start from,this has really helped me out, thanks agin.