Need Help Getting Low FPS on games

Is this happen when playing L4D only? what about the other games?
Have u installed the latest driver for your gpu?

other games too... i used to play crysis and crysis warhead before and it worked fine.. but now this is happening.. yes im using the latest gpu driver

my processor hits 70-100% when playing games... is this the cause of the low fps?

Your CPU is bottlenecking... Still, i'm not sure about that.
What about your gpu temp when gaming?
Is it normal or hot?

gpu temp 41-45 only and its overclocked to 800/1900/1000

it's normal...
What your CPU usage when idle?

around 1-5% cpu usage when i idle

Then, your pentium D is your trouble...
U might want to upgrade it with a better one...
What is your motherboard? brand? type?

duh, pentium D is a dual core p4, which is a excellent heat creating machine compared to a processor

maybe.... barbecue on it??  

im using asus p5kpl-am se motherboard... im using coolermaster v8 on my processor thats why it doesnt heat up, i tried running 3dmark vantage and i got P3919 , GPU = 3243 and CPU = 10473

Still... upgrading to quad core maybe good option.
Do u want to upgrade?

im planning to get Quad Q9550 if its any good

Of course it's good...
U will see the increasing works significantly from Pent D to quad...
Also, your coolermaster would "cool" enough to cooling down a quad.

the only thing that troubles me is that what if its my video card that is defective

Nah, you'll just burn everything.  

let's see your gpu temp first and posting here....
U could try your card to another system and see if the same thing happen when playing games....
Any vertical lines or artifact on your monitor when gaming?

Gpu temp is around 44-51 only never goes higher than that.. i think it really is my processor.. any idea what video card would go nice with Q9550 processor?

Yes, it's your processor...
Your 9600GT would still enough gaming with decent quality...
It's okay if u want to upgrade your vga, but the 1st priority is your proc....

Q9550 will run good with nearly any GPU setup (haven't seen 5970 crossfire benches on yorkfield yet hehe). Since you know that, from here on out all you have to do to get more (gaming) performance is upgrade your graphics card.

at first i was planning to get core i7 940 but when i asked for the price it was hella expensive so i tried asking for core i7 920 it was alot cheaper than 940 but if i use core i7 that means i need to get a new motherboard and add ram... the 5970 is also expensive mainly because its new.. ill think ill just wait untill they release another one untill i get the 5970... lol the price is just not practical.. currently looking forward how much i could overclock q9550 when i get it next week

If your motherboard is up for the task and you have some decent cooling you can get the Q9550 up to ~4.0ghz. 3.4ghz is the average 'easy' OC w/o raising voltages, unless you get lucky like me and get 3.6ghz without raising them.