I tried atomicrocketturtle's php upgrade but it failed. Apache wouldn't start anymore. So i rpm -e all of his rpms and reinstall packages from PSA rpm installation base dir, except for apache( it was recompiled to "fix" the 256 issue) and MySQL wich were previously upgraded to V4. All services are fine, except for the cp.
Now when i try psa start it fails. I get an httpsd bus error message. If i try to reinstall Plesk (rpm -Uvh psa.rpm --force --nodep) will it overwrite all the accounts, files, mailbox, mysql tables, etc...? Or will just put the binaries, scripts and conf files? How will it affect httpd.conf and every vhost.conf file?

Thanks for any help....

Create backups of httpd.conf and httpd.include and you'll be fine:

cp httpd.conf httpd.conf.old
cp httpd.include httpd.include.old

Reinstall the psa rpm, because it will fix this. Plesk stored data is NOT affected by this install (actually is more an update).