[2Jedismom]

And here mentioned again:

Devilry of Saruman!' cried Aragorn. 'They have crept in the culvert again, while we talked, and they have lit the fire of Orthanc beneath our feet. Elendil, Elendil!' he shouted, as he leaped down into the breach; but even as he did so a hundred ladders were raised against the battlements.

And here again:

I will ride with you,' said Aragorn. Taking his leave, he returned to the walls, and passed round all their circuit, enheartening the men, and lending aid wherever the assault was hot. Legolas went with him. Blasts of fire leaped up from below shaking the stones. Grappling-hooks were hurled, and ladders raised. Again and again the Orcs gained the summit of the outer wall, and again the defenders cast them down.

[HairOfTheDog]

Yes - I think Helms Deep looks great in the snippets of film we have seen. Very much like I imagined the scene too... So everyone just forget about any orc wall-climbing you may have seen... or maybe Jackson's Moria orcs are a unique mutation of wall climbers, and they are the only ones that can do that. However you wish to file it in your own mind so that it works!