AOL stands for America OnLine, so I do not think the change is necessary.
As for v4.0 being larger than 5.0, this could be due to many things.
Such as not having optimized graphics in the 4.0 version.
Changes in the installer program could have produced a different size.
Optimizing the code, and removing 386 instruction sets during compile time would reduce the version 5.0 filesize over the 4.0 version.
Switching the compiler to a newer version can produce smaller code.
Reduction of including certain dll files from the install package that are commonly found on Windows helps.