I assume you mean 3 GHz and 1.5 GHz, not GB.

The processor on your desktop is twice as fast as your laptop's CPU. That makes a big difference. Over twice the RAM does not make up for that much difference in the CPU speeds. RAM speeds things up only when there is not enough memory available and the computer has to use the swap file. Also, the RAM on your laptop is probably slower than the RAM on your desktop.
--Judy M.

What happens with a clean boot?

   How to configure Windows XP to start in a "clean boot" state

>> I doubt whether the cpu speeds make a perceptible difference.  >>

But one is 1.4 GHz and the other is 3 GHz. I can tell you from personal experience that the difference is VERY noticeable. I can tell every single day because one of my computers has a 1.3 GHz Celeron CPU and the other had a Sempron 3200+ (now upgraded to an Athlon 64 X2 4200+) ANYONE would notice the performance difference between them.

Of course, I can't say the CPU difference is responsible for whatever the speed issues are, but I'm not surprised that the desktop is noticeably faster than the laptop.
--Judy M.

% allocated to Hardware Interrupts

Attachments
	Name:   ProcessExplorer.jpg	Size:   128 K

I have already attached a copy of the Process Explorer window which summarizes all processes to my previous message.

Please tell me more explicitly where you are looking. It would be nice if you would attach a picture as I did.

% allocated to Hardware Interrupts can be quite high

It's probably due to some device or port misbehaving. In the following discussion, it was traced to the FireWire port.

   High CPU usage without any program running

Start by disconnecting hardware.