my current specs are: P4 1.7Ghz 512 SDRAM (pc133) Radeon 9600 128mb if i added some more RAM to my system, would there be any noticable boost in the performance of my pc when i play games(mostly Unreal Tournament and Counter-Strike)
Well, that really depends on what OS you're using. With Windows 9x, you definately wouldn't notice any boost in game performance at all. 9x uses such a small memory foorprint in your 512mb of RAM that you probably aren't even using any more than 300mb at any given time. If you're using Windows XP though, you'd probably gain some benefit from another 512. In its untweaked default state, XP uses 256mb+ and whatever is left over is used for your games. Even in that situation though, you probably wouldn't gain that much performance from a RAM upgrade. I'd only go for it if you can get a killer deal on the RAM.
Well on my system XP uses 100mb right off the bat so I think that 512mb is the sweet spot regarding the price/performance ratio. What you would need IMO is DDR ram. That would increase your performance much more than another 512mb. Of course you would need to change your board.
I've tried 768MB in my main box and wasn't able to tell any difference in any application over the regular 512MB. Granted, I've got a Radeon 8500 in there, but I wasn't making use of the extra 256MB. 512MB is the sweet spot, and with your setup, I'd advise against buying any more SDRAM. It's old stuff now. Save it for a new mobo/CPU/DDR combo that isn't a bottleneck for the Radeon.