If you just want to clean up files from browsing, just click on Tools - Options in Pocket Internet Explorer to delete cookies, temp files, history, etc. The highly recommended cleaning utilities (e.g., SKTools, MemMaid) are not free.
Thanks a lot guys/gals. It sounds like for freeware it would be fastcleanup 1.3. I just didn't know if it was ok with WM5. I don't think I need anything too fancy.