BaseSystem.pkg.1518yN2yy Folder After Clean Install of 10.5 - 10.5.8

Hello There,

After a "clean install" of 10.5 then moving to 10.5.8 on my friends iBook I was left with this folder in what a guess would be called the root folder. (Macintosh HD)

(The folder that holds Applications, Library, System and Users.)

It's named BaseSystem.pkg.1518yN2yy It holds 12.7 MB worth of material..

I was wondering what if anything I should do with this folder?

I remember reading once that you could delete it, but others have posted to just leave it alone.

Before I give my friend back his computer I would like to find out what if anything I should do with this folder.

Thank You for your time,

Eric