Warcraft III and WoW doesn't use as much system resources as any of the recent first person shooters. 512MB of memory should be more than enough. If they're the only games you wanted to run, don't waste any money upgrading memory.
You just reformatted the harddisk, so malware shouldn't be a big issue. Make sure to get the latest DirectX and a proper video driver for the graphics card. Windows include drivers for all the brand name graphic cards, and installes them automatically. They're not good. Download a copy of the real driver from majnufacturer's website. Also, if you have Service Pack 2, get rid of it. It makes games lag. Getting SP1 is enough.
I just reformatted my whole computer and added Warcraft3 TFT and World of Warcraft back on my computer. When I l[pay both games, I get slow gameplay for about 10 seconds, then it goes back to normal. In WoW i get around 40-50 fps. It drops to 20, then goes down under 5 fps and does this about once every 3 minutes. Same thing with war3 but people say im lagging. Could this be a memory issue? I only have 512mb of ram so I might buy another stick. Im not sure what it is but its never happened before. I have a ati 9600 xt graphics card, 1.8 ghz processor, and 512mb of ram. I have all of my drivers downloaded and all of the windows updates installed. What should I go/buy to fix this problem? thanks in advance.

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