2003-2007 Compatibility

So far I've worked out that a 2003 user must install the Microsoft Office Compatibility Pack to open/edit/save 2007 .xlsx files.

If I have functions such as DOLLAR that usually require the Analysis Toolpak for 2003 users, the Compatibility Pack itself is enough for them to view the results, right? I presume that this is the case but I want to make sure, and I can't find confirmation with either Google or Microsoft's website.

Any information about compatibility would be appreciated.

I don't have Excel 2003 any longer to confirm, however I wouldn't make that assumption. Even though you have the Compatibility Toolpak installed, I don't believe any functions new (built-in)to Excel 2007 will work in 2003 without modification or - in this case - turning on the Analysis Toolpak add-in.

You don't need the Analysis ToolPak for 2007, the functions are built-in now

For backwards compatibility,develop in the oldest version