Toilets, Sinks, Showers, Tubs and Disposals - Trouble fitting P-trap with new sink

I don't do much plumbing, but after putting in a new sink, the drain and j-tube are too close for p-trap pipe. They just about touch. What is the solution? Shorter j-tube?

http://img145.imageshack.us/img145/305/img032n.th.jpg (http://img145.imageshack.us/my.php?image=img032n.jpg)

Loosen the nut at the wall, slide the j-pipe out, cut to the correct length with a pipe cutter (or very carefully with a hacksaw, clean off the burrs and don't distort the shape of the pipe). Temporarily fit the trap to determine the right length.

You may need a new rubber or plastic washer under the nut, if so, slide it on before cutting, to prevent damage from any sharp cut edge or burr.

There should be a nut there, but I can't see it, the supply line is in the way in the pic.

The nut at the wall is metal and almost seemed welded on when I tried to get it loose. I'll give it another shot after work.