Ok I looked at the guide but I don't understand this... I have a Radeon 9800XT, and a P4 3.0ghz (don't know if it is a Northwood or Prescott). 1024 mb of RAM. I was just wondering... I get really **** FPS on some maps, usually the larger open area parts, and ESPECIALLY custom maps with large open areas, even if they have just large flat surfaces. I shouldn't expect this with a 6+ year old engine. I was wondering, I heard that Half-Life has some FPS issues period, and is this the reason or is it something else?

NS seems to have some unpredictable FPS issues and some say Half-Life does too. In case you haven't, turn off your anti-virus while playing. Make sure you're in Open GL mode. A lot of people I know got much better FPS when they upgraded CPU, but that surely can't be your problem. I run NS in 800x600 (heard it worked better), 16 bit colour, OGL mode on an Athlon uh..... 2600+ ? with a bottom end GF FX. FPS tends to be about 60, thanks to windows 2000/NT/XP locking the refresh rate down.

I can't imagine why it would run slow on your machine.

Well I know that NS/HL (more likely HL) doesnt seem to like ATI cards (or is it the other way around ) as I've just upgraded to a 9600XT and Im getting worse fps than my old gf4mx440

Dont play HL with higher than 2xAA and 2xAF.