Bob, have you got a program like Paint Shop Pro or similar? You can specfiy the HxW in pixels then resave it and use that saved version as your avatar. You can also do this in the Paint program that comes with XP. Go to Start, All Programs, Accessories, Paint. Open your picture in there then go to Image/Attributes, click the pixels box, resize, save a copy. (Sorry, I'm assuming you have a PC not a Mac, but a Mac will have a similar basic graphics editor also I assume).
John