Trying to Upgrade 5.2.1 to later version

[A. Clausen]

I'm a complete newbie to FreeBSD (coming from Linux).  I bought (for 
cheap) a boxed set of FreeBSD 5.2.1, and am looking to upgrade it for 
XOrg and the latest version of Postfix.  When I try to use sysinstall, I 
get the following error:

Warning:  Can't find the `5.2.1-RELEASE' distribution on this
FTP server.  You may need to visit a different server for
the release you are trying to fetch or go to the Options
menu and to set the release name to explicitly match what's
available on ftp1.freebsd.org (or set to "any").

Now, I'm pretty sure that the problem here is the age of the release (I 
guess two years old), but I was wondering if there was a workaround.

-- 
A. Clausen