Ok, first off, there's no such thing as a "Windows 2000 program". All apps are Win32-based. There might be apps/tools that are built FOR Windows 2000 specifically, but they should all RUN on ANY Win32 platform.
That said, the bottom line is this - if you have to connect to a domain at work, you need XP Pro. Home won't allow you to connect to a domain easily, and when I say "easily", I don't mean it's a minor nusiance, it's a major one.
Mike