Help me keep my cool?

I just put together 2 identical computers consisting of: Intel 2.8GB (800mhz) HT Prescott. It's on an ASUS P5GD2 Premium motherboard. My problem is the fan was running at 4500rpm and operating system menus were slugglish. Everything was hot to the touch and loud!! The temporary answer was to remove the side cover and place a 14 inch house fan directed at the side of the computer. Ironically, Sonata has 2 seperate 120mm fans. One for the power supply and one for the chassis. But, thanks to the house fan placed 2 feet away everything is running quiet and cool. I have one Serial ATA hard drive and one PCI Express video card and 1GB memory running. Any ideas or is my house fan a permanent piece of the computer...it's not an attractive proposition to me. Perhaps PCI Express is premature. Oh, and to top it off, this is only happening on ONE of the computers...everything about them is identical, except one has Windows XP pro, and one has Windows 2003 server.