How do i make that rounded/smooth outline for 750x450 site?

hi there.
I'm building a flash site and i'm trying to make that nice smooth and rounded outline (just a simple dark grey line with rounded edges) to put in the background

I cannot seem to do this! I feel very stupid, as i'm not actually bad with photoshop. I've made a 750x450 photoshop file and just cant get it to look nice.

Does someone have a simple method for this? How can i do it to the very maximum size that will fit on the 750 450 doc?

the perfect example is of the main flash part of the macroedia site here here

regards


coogie

If its a flash site, why not create this part in flash?

It will be vector.... and smooth, not to mention the load time would be quicker than if you bring in some raster background graphic.