Upgrade RHEL3 x86_64 to RHEL4 x86?

[Terje Bless <link pobox com>]

I have a system installed with the x86_64 version of RHEL3 that I need to
upgrade to RHEL4. Now since the system is one of the EM64T (Dell PE1850) boxes
that doesn't actually need the 64bit edition of RHEL, I'd like to upgrade it
RHEL3-x86_64 --> RHEL4-x86.

I would initially guess this should work more or less fine — a few minor manual
cleanup jobs post-upgrade aside — but since the installer explicitly warns me
that this “probably won't work” — and I can't risk experimenting too much on
this particular box — I'm getting cold feet.

Has anyone tried this?

Or speculate what the likely problems are?


-- 
  >You mean you've been out of the secret-loop these past 5 years?
  No, no. Of course not. BBEdit has been leading a “secret life” for the last
  five years, too.     It just involved stiletto heels and fishnet stockings.
                                          -- Jon Guyer <jguyer his com>