The amount of RAM and the type of RAM is one of the biggest factors in loading times. 1GB of RAM or less will give you a long loading time.
Find out what kind of RAM your mother board takes, check there is a empty RAM stick slot and buy some more if you can.
If not, boil some tea or mix up a u-boat cocktail whist you wait for it to load.
Defragmentating your hard drive will have a positive effect if you have the time for it. Remember not to touch your PC when you are doing this and disable your screen saver first!