Just discovered a feature of Win XP-- there's colour-correction software built in! Right-click on the desktop, go to Properties--> Settings--> Advanced--> colour correction tab. From there, you can adjust contrast, brightness and gamma for the RGB channels separately and together.

By comparing a colour image to its printout, you can tweak your screen's colour profile till it matches your printer! Really helpful! And free too! Okay, enough gushing.