If XP's language bar is anything like w2k's language switching fujizmo ("internat.exe"), the only way to get rid of it permanently is by having Windows install only one language on your pc.
-Believe me, when I had w2k I searched high and low for a solution, and there was no other way out of it.
For example, as I have to use French for my keyboard to work properly, w2k would set itself up to switch between French and English. That's because my installation CD was in English.
And just like you, there was no way to disable that option. (Save deleting "internat.exe", which would still reinstall itself from time to time.)
That's why when I got XP, right in the installation--in "regional settings"--I made sure to delete English and keep only French.
-And no language bar ever showed up on my XP.
So if you're not about to re-format, and you can't find an easier solution, maybe you should consider going to :
«Control Panel > Regional and Language Options > Languages tab > Details button» and remove any superfluous language(s)...