you could use mactheripper and then whatever the replacement of visualhub is these days (coder no longer supports it) but there is a free alternatvie. just forgot the name
i have no idea on the program requirements are though
You can use the Handbrake command line program - http://handbrake.fr/rotation.php?file=HandBrake-0.9.3-Win_CLI.zip - it has minimum requirements of 256MB. It's quite simple to use. I did this to rip my sister-in-law's wedding video on my parents-in-law PC.
Really, RAM is so cheap these days you should upgrade ... you should be able to get 1GB for less than $20.