Office Addins (PIA)

[LeAnne]

I've developed a word Add-in.
I need to support Office XP and Office 2003.

I've learnt that if using Office XP, then my product needs to be using the
XP PIAs and vice versa.

Thus at the end of the day, I need to build two version of my application,
- One which references the XP PIAs (to be installed on computers with Office
XP)
- The other with references to Office 2003 PIAs (to be installed on
computers with Office 2003)

Questions:
1. Do i need to install the PIAs into the GAC (cant i use private
assemblies - placed in my application directory)?

2. Is there any easier way (rather than building two versions - or building
two setups - one for XP and one for 2003)
I.e. building a single setup, which via a custom action will install the
necessary PIAs and also the required assemblies which reference the relevant
PIAs.