Are you running any other programmes that could be causing this?
Have you recently changed your security software?
When was the last time you scanned for viruses/malware/etc.?
Are using a wireless connection?
Much more information is needed.
When you say "lag" do you mean just the connection - or the actual PC slows down?
Is the hard disk going nuts when it's slowed down?
Sounds like excessive paging
i have no idea what that islol
<-- noob
It's when you don't have enough RAM, or some of your RAM is broken. Windows can't fit enough of the game in RAM, so uses Hard Drive instead. Hence the questions about Hard Drive activity.
Can you see 4GB RAM from within Windows?
no idea on the brand its a 850W and all i have in there is mobo,2 HD's,ram and the gfx.How about power - what's your spec? I'm particularly interested in your brand of PSU, and all the things connected to it.
How about malware - how's your security setup - could you reinstall Windows conveniently?
Check your Scheduled Tasks for anything like defragmenting, virus scanning - things that use lots of resources and aren't really necessary.
CPU temp is high, vacuum your cooler, give your case a good clean - see if you can do something with it.