ok ok ok guys … don’t get all riled up here
blenders material system isn’t all that intuitive for folks coming from other apps. that’s fairly well known i think. but it is just as powerful, especially when nodes get thrown into the equation. just takes some getting used to is all.
when you press ‘add new’ material, you are essentially creating a full copy of the material that was selected when you pressed ‘add new’, including all textures, settings etc … this IS nice, if that’s what you want, but can be confusing if you don’t understand blender’s workflow. it just takes some getting used to.
so you ‘add new’ material, you’ve got a LINKED copy of the texture from the original material. go into the texture slots, and delete the linked texture, then add a new one. DON’T just change the linked texture. or, as harkeyman said, click the ‘make single user’ button to turn the link into a new texture. then you’re free to change the texture as needed without altering the original material.
did that make sense? the wiki for 2.49 explains how this works in much greater detail, although the specifics of doing it in 2.5 are rather different. perhaps if you are a completely new blender user, you should use the 2.49b release instead of 2.5, because, as harkeyman said, 2.5 is in alpha, and is in release only so that the community can use it and test it to work the bugs out. It’s a complete re-coding from scratch of the previous versions to make the code more stable and easily expandable. In many regards. 2.49b is more functional (i.e. - less crashy and the features are all there, except the newest ones like smoke, volumetrics, et al) and is MUCH better documented at this point. The wiki manual will be able to help you a LOT more if you use 2.49b.
hope i’m helping, and not just blasting oxygen into the fire