As required by law:
Awsome job, great idea!
FYI:
I have found I can get the compressed portable_firefox_1.5_en-us.zip down from 6,643,139 bytes to 5,258,684 bytes using Tugzip, http://www.tugzip.com/ ,and 7z compression.
This is a significant savings especially for download bandwidth.
Results
portable_firefox_1.5_en-us.zip
Original (download from sourceforge) - 6,643,139 bytes
7z Ultra Compression - 5,258,684
7z & a Self-Extractor - 5,343,676 (79% current file size) 1.29MB saved
I would recommend considering use of 7z and self-extractor to lower your bandwidth overhead.
Regards
Joe
Disclaimer: I am in now way associated with tugzip or the makers of 7z. I am a recent convert from the zip/tar world. My plans for world domination will continue through my many nefarious compression schemes... Bwa haha!
Actually, I'm aware of that, but wanted to keep it as a ZIP for now as it's pretty universal.
I'll be using a self-extractor or a full installer (with upgrade support) in the near future.
Sometimes, the impossible can become possible, if you're awesome!
Sourceforge is very generous when it comes to bandwidth and webspace.