Yes, that was helpful, wasn't it
DC9, I've just had a look on Amazon for the PC version of Halo....you might want to read some of the user reviews there to see if they mention specs...
I've just found this quote: "It's a hardware eater this game, no question about it, but with my Athlon 3.2GHz and [pretty mediocre] ATI Radeon 9500, I was able to conjure up a very acceptable frame rate."
I imagine (s)he means an Athlon XP 3200, or Athlon64 3200. From what I remember the Radeon 9500 graphics card came out in 2002, and was either 64MB or 128MB.