Very slow browsing

I have tried rapierau's fix. It seemed to work on a couple of sites but other
sites continue to load very slowly. My company's site took over 3 minutes
just to load the front page. I am running Vista Home Premium on a Pentinum D
915 Processor, 1024 MB RAM and 250GB hard drive. Please help as my old 750mhz
laptop running Windows 2000 is outperforming my new computer and ****ing me
off.