Create Folder and replace if exists.....

I have a question about creating a folder.
I want to create a folder with the Replacing syntax so that if the folder exists it’s over written.
I’ve tried several way’s. I can create the folder but when I run the script again, it tells me that the folder already exists. I need to over write it everytime.
Any hints?
This is what I’m working with…

 set thefolder to (make new folder at startup disk with properties{name:"TEST"}with replacing)

Replacing doesn’t appear to apply here. Try this:

tell application "Finder"
	if exists folder "TEST" of startup disk then
		delete folder "TEST" of startup disk -- moves to trash
	end if
	set thefolder to (make new folder at startup disk with properties {name:"TEST"})
end tell

Rob,
Thanks a million. It worked.