Last time I tried Prefix it didn't work or at least wasn't as convenient as I was expecting. I wish I could give more details than that but I can't remember now. I was and still am really excited by software like Prefix, however.
This is the only one of the bunch that I've been able to install some packages on RHEL5 and RHEL3 that I'm stuck with. (And even then, only with too much effort bootstrapping.)