As said check your Irq settings in the bios, it should be set to auto or Pnp mode plug and play. Turn off any device in the bios you do not use on the computer, examples can be serial devices or the parallel port, most of these use an Irq so turning them off will free some up.
My other note to you is you have a 9500gt graphics card, they are known to use system memory as a texture cache, So if the case it will be eating a large chunk of the system ram. You will have very little left to run the OS and the result will be the swap file that uses the hard drive will come into effect. Buying more system memory should speed things up if the case, 1Gb of ram is very poor and will result in slowdown of system response if it running on low memory due to what I have related to you.
Have a look in system information in windows, my bet is you have something like 300Mb of system ram free.