i just recenly "upgraded" my computer with a new 120gb hd and a new stick of 256mb PC2100 DDR. i also attempted to install a new processor, but it wasn't compatable with my motherboard so i ended up putting the old one back in. now, my computer is laggy as hell and whenever i run more than 1 or 2 programs at once, my CPU usage maxes out. i dont understand this....it's the same processor i had before, and i have even more RAM now. why is it lagging?