I know that getting updates for a machine from that same machine is a no brainer while that machine is on a fast connection. Is there a way to download everything possibally needed post xp service pack 2 for any machine?

I built a machine for a customer, installed xp with service pack 2 and it doesn't have fast internet connection. I don't want to spend hours downloading all the updates that have been released since sp2 using a modem connection from that machine. Instead I want to do it from a different machine which is on a fast connection.

Microsoft's download center website confuses the hell out of me. I am not sure what to download.