Suspiciously Conformant Install Sizes

I needed some hard drive space on my Windows XP machine, so I went to
Add/Remove Programs.
Office XP Professional shows up as 273 MB
Office 2003 Professional shows up at 273 MB

I find it suspicious that they're the same size. Will trying to remove
XP remove 2003?

I also see three entries at 988 MB
..NET Framework 1.1 Hotfix
..NET Framework 1.1
Visual Studio .NET 2003

I'm not going to remove any of those, but are they all talking about
the same 988 MB, or are the three of them together taking up almost 3
GB?