Well GIMP is free, and there are a lot of tutorials available online for it to help new users (ditto with Photoshop, which can be adapted to GIMP pretty easily).
Here's a quick idea of how it might be used for helping decide on colour combos:
Once you've got the basic blocks of colour in place you can alter them easily for more variations:
Einion
This is absolutely tremendous...just incredible.
Sometimes I feel like a pair of brown shoes with a tuxedo on this website.
