Problems need help

It just might need a good clean whipe on my hdd cuz the guy that built this didnt listen,this is y i build my own pc's. I have 3 hds,a gfx card,2 dvd drives,4 fans,well 5 on the cpu,this ide connector nic card thing,a processor.I think thats it,so when i used my old machine. A 3500 64 amd athlon,7800gt,2.5 gbs of ram,2x120 mm fans,an audigy sound card and 2 hds i could play on my games fine..even the next gen fine like splinter cell da.

My question is this pc blows this one away i have the same video card,7800gt,1 gb of geil ddr2800,e6400 duo,3 hds,250x2,80...etc well my back fans dont turn on.my processor is running at 55 c wich it shouldnt im just wondering what is going on. I go to play a game bf2 and i lagg madly i skip everywhere and i shouldnt be.Its annoying me madly man,does anyone know what he problem could be? yeah i do have the latest drivers for the card.