Wow, I will have to see if I have that script tomorrow when I turn on my desktop, in bed now with the iPad.

Thanks Graechan, see ya tomorrow.

@Graechan, the script worked but when I pasted it into a larger layer, it wasn't seamless.

Molly - the pattern is seamless, the problem is with the initial size of your pattern and the area you are trying to fill, say I create a pattern 300px * 300px and use it to fill a canvas 1000px by 1000px. The pattern would repeat 3 times (300px*3=900px) and then have to fill the remaining 100px so only using a third of the pattern, this then makes your pattern seem offset or not seamless.
The best solution I have found to get around this is to create a new layer larger than my canvas area but which is also a multiple of my pattern size, so in this case I would create a layer 1200px * 1200px (300px*4=1200px), I would then fill this layer with the pattern. Then centre layer to canvas size and final crop to canvas.

O, thanks, I didn't know that. I thought it would paste into any size canvas as a seamless pattern.