yeah. go into your pictures that you've uploaded. find a new pic, and click 'edit' then something like 'set as default pic'.
Go on your home page on myspace, and then Upload change photos, and then go down the page until you see your photos, or they maybe in a folder, then you click on the photo you want, and then you go on set pic as default..... Should work then, can take upto 24 hours though