Just a reminder that AIX 5.3 goes out of support on 30 April 2012. That means the end of standard support. If you must keep your AIX 5.3 systems and can't upgrade it (you probably can, more easily than you realise), you could create a versioned WPAR running AIX 5.3 on an Power7 system within and AIX 7.1 logical partition. You can build it all with a mksysb restore.
For more details, see this document.