Need some general system overclocking advice

Hello everyone, I've been reading these forums for a few weeks now but have never posted until today, after delving into the world of overclocking on my system. Now I suppose you should know my specs to answer my questions. This is a PC I built on a fairly low budget so it's not amazing

Athlon 64 3200+ OC'ed to 2.25ghz
Geforce 6600GT 128 MB OC'ed to 586/1086
2x512 MB Corsair VS DDR @ 450 mhz? (I'm not too educated on memory)
A8N-SLI socket 939 motherboard

I think thats all you'd need to know, but anyways... Today I spent some time using the Ntune and AI booster utilities that came with my driver disc to toy with the settings on my GPU and CPU for a while, mostly the GPU since it is a weak point in my system. I have the card set about as high as I can without getting any artifacting while running 3dmark05 (I'm up to 3966 marks ) but the processor I just set to 2.25 and left it for the moment. Now as I said I have no idea what performance differences come from changing the RAM frequency so I would like to inquire on that subject, and also how high you think I could push my 3200+ on a stock cooler without it melting heh. Thanks in advance

Oh by the way all the cooling is stock.