Thanks NJBlackBerry, I found a folder whose name was my PIN right where you said it should be. I was excited initially, as the date stamp on it even matched the time when I was doing the install. But there was no pin.ALX file in it though...
The only ALX files on my PC right now are all in C:\Program Files\Common Files\Research In Motion\Shared\Loader Files\ I have no pin.ALX file anywhere on my PC in fact.
What to do now? So they aren't in the big backup file made just before my first install? (called "LoaderBackup-(2009-09-02).ipd")
PS Was there a way to have backed up the apps separately that I should do next time in case it happens again, seeing this method of getting them back may not always work?