You seem to be confusing j-channels with flashing.

These are not the same thing.

Traditionally, j-channel was a siding trim molding fastened around windows and doors which then received the siding.

Some modern vinyl windows, however, incorporate a j-channel right into the window itself. There is no need to add another j-channel.

Flashing, on the other hand, is aluminum that is placed over the nailing fins of new construction windows that prevents water intrusion behind the unit.

ALL windows should be flashed for a proper weather seal regardless if they have a built-in or added j-channel.

Here is a helpful link describing and depicting proper flashing application:
http://www.supersealwindows.com/guide/pen_flsh.html

Here is a helpful link showing an integral (built-in) J channel on one type of vinyl new construction window: (PDF Format)
http://www.insulate.com/pdf/cwindows/NCXTCutaway.pdf

[This message has been edited by homebild (edited February 17, 2003).]

OK, so if I remember correctly their is flashing around the window (Too cold to go outside and look)

So we will assume J-flashing is their...

If the windows that were installed had J-channels already.
Than when I look at my siding around the windows, I should not be able to see through the sides of the vinyl where water and air can get in.

My vinyl siding just props up against the sides of the windows. It is visible to the eye that air and water could get in.

Thanks for your response Homebild

I ordered windows and forgot to ask for jchannell option built in and he said I could just knotched it with a knife ??