well it all bulls down to what operating system you currently have installed. if you have Vista then im afraid that is your problem, it is a massive resource hog when it comes to memory, graphical and CPU Usage.
down below are a few links i use when i tweak vista, please be careful when tweaking the System Services, make sure a proper person knows what he/she is doing, disabling some might cause your pc to screw up.
haveing too mnay programs starting on start up, click the ORB or START, and click RUN.
type in " MSCONFIG " and click START UP.
disable all the programs you dont want to start up,
virus scanner, fire wall yh leave them alone, but stuff like
windows messenger, other ullititys that you dont really need running.
if you have XP do the above with msconfig.
use Housecall, online Virus Scanner just to be sure.
i always use it, does the job :).
PS: im not shouting with the caps :), alittle message thingy >>
Did you leave the Caps Lock key on? Using all caps can be perceived as shouting.. lol