The monitor would have been something like this HP L2335 LCD monitor from 2004 (this [1] review is from 2005).
According to benchmarks [2], Half Life 2 was pretty vertex and/or cpu bound, so a mid-to-high range GPU ($300-$400) would be able to run at that resolution.
According to benchmarks [2], Half Life 2 was pretty vertex and/or cpu bound, so a mid-to-high range GPU ($300-$400) would be able to run at that resolution.
[1] http://www.anandtech.com/show/1729/2
[2] https://www.anandtech.com/show/1546/