Will I need an additional fan in addition to the stock one?
Probably not with a single Samsung hdd. Front fans usually only cool the hdd and not help much with the rest of the case
How much will I gain by moving to 3000+/939?
Much, if it's the new winchester core CPU. The power draw on those CPUs seem A LOT less than anything else. It'll both help you run your CPU cooler slower/quiter and also draw less power from your PSU, releasing less heat.
Will Arctic Silver 5 make any difference?
IMO, Yes. Arctic Silver is kind of apply-it-forget-it thermal paste. Most others I've seen dry out over time.
SAMSUNG 160GB 7200RPM SATA
Try to get one with a NIDEC motor. The other one is JVC. You want the NIDEC one. The brand is printed on the round metal on the underside of the harddisk.
For video, that 9600XT is a good cheap choice. It's not very powerful but the 9200SE just isn't for games, the performance is extremely lousy. There may however be an issue with that passive heatsink and your MSI motherboard. Other people in the know will probably drop in on this.
Cooling a high-end Intel CPU is becoming almost impossible. I'd stay away from them, especially considering that you want a gaming system which is AMDs forte.
9600XT is a good gaming card for today - average performance, good price, passive, etc. However, if you want any kind of longevity, it might be a better idea to go with a stronger card and install some version of Arctic Cooling VGA Silencer on it.
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