XP will probably install a basic driver for that card on its own, but if you want the full potential to be realized, you need to install the latest drivers from ATI/AMD.
Also, none of the other things you mentioned will do anything to cause any real significant increase in game performance.
I bought a Radeon 9600PRO 256MB 128-bit DDR AGP Video Card, and a gig of ram. Before I couldn't play any games but now I can, so I bought the Sims 2 and installed it. Graphics are okay, but the game performance is extremely slow. This is the only game I have so I have nothing else to test my computer with.
I've tried everything to speed it up - defragmenting, disk cleanup, deleting a few gigs of my stuff, but it's still really slow. I'm guessing that it's because of my harddrive. It has 40 gigs, but I'm already using up 28 gigs with 12 gigs of free space. Help, please?
My system specs:
Window XP home edition
2.4 ghz Intel Celeron processor
1 gig of RAM
The said video card
40 gb hardrive (12 gb free space)

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