Property Extract is a small application that lets you save packages in DLL, OCX and EXE files or libraries such as icons, pictures, bitmaps, HTML files, avi movies etc.
How it works is simple: point to the location and destination folder of the file where you want to remove the content.
At the resource extract interface, you can select the resources you want to get out, such as those you really need to save. You can scan the subfolders inside the file and set it to save the BMP file as PNG.
Finally, it is worth mentioning that you can run an asset extract from the command line, which is something that more advanced users can appreciate