I'm using an xbox controller and am having a bad time against the AT ATs. I can launch the cable but can't trip up the walkers with it. Do I need to brake or something? If so, which buttons activate the brakes as nothing seems to work? I'm using the default layout as mentioned elsewhere in this forum.

Any help is greatly appreciated as I remember this was the sticking point for me years ago in this awesome game! :)

Yes you will need to use the brakes. Snow speeders have a left brake and right brakes, you can set which button control them in the option menu. Once you use these it greatly helps with tying up the AT-AT after you do three loops.

Strangely enough I very rarely used the left and right brakes on the speeders. Normal braking was enough for me to take down the AT-ATs with the cable. The only time I really used the left and right brakes was when I needed a sharper turn. I have used it in taking down AT-ATs, though, but usually only when I made a mistake and had to turn a bit tighter. I daresay using them would have been a better option had I tried using them earlier though as tighter turns mean less distance and therefore taking the AT-ATs down faster. So, yes, recommended, but not essential.