Hi mrchips, welcome to itsallPC
This would be an absolutely excellent deal. From what I remember, the 5000t series systems were quipped with socket 370 motherboards, which would mean Pentium III or Celeron processors, and all the trappings of such an antiquated architecture. The Sempron 3000+, basically a continuance of the Athlon XP architecture, would outclass anything that the original system has installed.
Although the architecture is not of the current generation, the system is contemporary; although low end/entry level. I do not agree that Compaq should replace a system that is fundamentally worthless today with anything better than that.