spydrwebb; That's odd, I don't see a transparancy tab? But it worked here just as I stated...perhaps because I only have a trial version?
I wonder if perhaps you are starting with a solid background rather then a transparent base? Do you 'create' a new transparent image and then paste your image to it or try to create a transparent background from one that is not?
One thing to note is do Not collapse the layers before saving, even in PSD this will cause the background to go white (however PSD allows you to collapse one layer at a time all the way down, weird) perhaps PSP has some simular quirk about it. Try leaving the layers and just SAVE AS and the save will (should) create a single transparent layer.
Example would be the ghost pirate I just posted, it was three layers (bottom blank, ship what partially desaturated, and the ghost pirate fully desaturated - both with different opacity settings). Then I just did a Save For Web {PSD thing, just Save As in PSP} and it saved what you see here.
As for centering try this, a test pattern I made more centering mine. It's not very professional but it works.
It's already got a base transparent layer so just click the bottom layer and past yours so it's inbetween the test pattern and base, then align it (red shows where to stay within, black is Out) then delete the test layer and save -> Do Not flatten!!
http://home.earthlink.net/~igohigh4/pngtest.zip
Squier; I know the feeling as a LOT of my stuff is not sutable for the general public and I have to stop and think about where I am before posting something....I cringed after noticing I posted a mermaid but it was too late...oh well, next time she must get bigger sea shells! ;p