My friend has a very low end computer with 128 MB RAM with Fedora 3 running on it. Can he use a USB stick as RAM. I know that wont help much. But people at different forums have suggested to use USB flash drive as a SWAP partition to improve performance. Will that help to some extent?

You can ask your friend to use a light distro like Puppy or DSL.They are optimized for older / slower hardware and can work quite well even with 128 Mb RAM.

Regards,

Sameep