A good computer to run the simulators?
The ATI 9000 is an okay card and will run your sims no problem.
The 2.53 P4 machine looks good.
I would cut back the ram to 256mb and maybe even the Hard drive to 80gb or less, if it has a CD writer then why have all that space? Also a 7200rpm drive would be a lot better as they are faster.
Then the money saved may allow you to upgrade to a ATI 9500 or GF4 Ti4200. Then you should be able to play all the current games and sims.
Did you realise none of those machines come with monitors?
SimJen