After a few false starts, the Windows Mobile 5.0 upgrade for the iPAQ hx4700 is available in North America. For now though, your only option is to download it. The upgrade is still not available as a CD that you can order. It should only be a matter of time – Maybe the CDs are being pressed as I write this.
If you click on the ‘More information’ link, the option to download the upgrade is available in the Ordering Upgrades section under Electronic Download. It is available for $39.99 USD.