Viewing Program Sequence very jerky (not smooth)

I am a new user of Premiere Pro CS3. While compiling a video composition and
while viewing it in the Program Sequence the playback is very choppy (runs
smooth for a few seconds then stops like it's refreshing and then starts running
smooth again. I am not running a duel or quad core processor and I am wondering
if this is a problem. Does anyone have experience running CS3 on a P4/3.4?

My system is as follows:
Computer: custom-built
Operating System MS XP Home
Motherboard: Abit AI7
Processor: PENTIUM 4 P4 3.46 GHZ ( 3.4GHZ ) 1M 533 478 (Hyper-Thread)
Memory modules: 2x 1GB (total 2GB)
Video Card: NVIDIA GeForce FX5200, (Graphic core:256-bit/memory
interface:128-bit/memory bandwidth:6.4GB/sec

As a test I also tried running the program on my laptop with the same result's
(jerky viewing Program Sequence)

Computer: Toshiba Satellite M65
Operating System: Windows XP Media Center Edition Service Pack 2
Processor: 2.00 gigahertz Intel Pentium M,64 kilobyte primary memory cache
Memory modules: 2048 Megabytes Installed Memory

Please advise us if you feel the system is sufficient to run the CS3 program
smoothly or is there a possibility of any set up problem. I understand that you
can assign RAM to PPCS3 but I can not find in the manual instructions how to do
this (just in case it's not recognizing not RAM.

Thank you,
Will Cherrington

      I am a new user of Premiere Pro CS3.