Before searching for a download link, it is important to understand the limitations of a portable version:
Searching for "Adobe Illustrator CS3 portable 818 MB" typically leads to unofficial, third-party download links rather than an official Adobe product. There is no legitimate "portable" version of Illustrator CS3 released by Adobe Critical Safety & Legal Warning Security Risk: adobe illustrator cs3 portable 818 mb link
However, downloading unauthorized "portable" software packages from third-party links carries massive security, legal, and operational risks. What is "Adobe Illustrator CS3 Portable"? Before searching for a download link, it is
Solid support for exporting vectors for web and animation. Limitations of Using a Portable CS3 Version Before searching for a download link