Thanks for the replies. I'd rather not 'auto-hide' the taskbar as there's several things on there I use regularly that I like to see all the time. Including the clock. Not majorly important I know, but a preference to how the screen set-up for me works best.
This is not the case - default behaviour in Windows 7 (and probably earlier, just can't check) is that maximised application windows automatically adjust to fit the screen depending on whether or not the taskbar is set to "auto-hide" or not.
This is what used to happen for me, and is how I like my windows to be when maximised. However, for some reason it doesn't seem to do that anymore. I was wondering if it's a 'side bug' from a recent Windows update? And thus if anyone knew if a fix will be released soon.