I'm playing the Lord of Terror mod, and my melee character can't touch a white dragon (colour - not in game description) he encountered. This is a Fighter 4 Paladin 8 CoT 1 with a whole lot of magical gear. Strength in the mid-20s, constitution and charisma around 18.

I barely get in one blow and then I'm knocked down and killed (with my Monk 13 companion). If I can't find a Thieves Hood (immunity to knockdown - but rather out of character for a Pally) what tactics are best?

I also have a dex Fighter 6 Rogue 5ish who took a dragon out above ground with elemental arrows while running around like crazy. Finished the dragon off in a trap field :)

Thieves hood wouldn't work for you anyway. You have to be a rogue to wear it.

Dragon Boots is what you want to find, and there might be others.

Discipline is the opposed skill check to resist without. How is yours? If you have it maxed, maybe something like "Greater Gloves of Discipline" would be enough to resist. But I would imagine dragons would get a lot of bonuses for knockdown and resisting without maxed discipline and gear bonuses would be tough.

If you can't resist, it seems like ranged attacks are the slow and painful alternative.

Great, thanks. Discipline is maxed out but will check for additional gear

The dragon also has to hit you to knock you down. How's your AC? Get it higher and the Knockdowns will miss a good chunk of the time.