I am trying to decide if I should upgrade to Windows 8 and one of my mission critical programs is PowerPoint 2003. I was wondering if Windows 8 x64 has PowerPoint 2003 support.
I beg to differ from the previous answer.
When you install any of the last few versions of Office onto a 64 bit OS the installation actually suggests you use the 32 bit version as you may encounter various issues with other software if you use the 64 bit version of Office. So, yes, it should be fine.
Also, according to the Microsoft support lifecycle page and PowerPoint 2003 support page you should be getting at least some form of extended support for Office 2003 up until 2014. So you would think that it would need to work on what will be a 2 year old OS by then. Sweeping assumption, I admit, but reasonable, I think, for this particular product.
According to Windows Compatibility Center MS Office 2003 is NOT compatible with Windows 8. However for earlier builds of Windows 8, RTM (build 9200) (with the Developer Preview, Consumer Preview and Release Preview) the compatibility center said Office 2003 was compatible.
Personally I don't see any reason as to why Office 2003 won't work with Windows 8, since it was compatible with earlier builds of Windows 8.