spinning picture

Hi everyone,
I'm trying to build an experiment on the Motion Induced Blindness (MIB).
I'm quite new with this software and I extremely need some help about making a picture spinning in the background for several seconds.
I linked a .ppt presentation so you can see better what I need to do.

[url]http://dl.dropbox.com/u/2604878/MIB%...%20concept.ppt[/url]

Moreover I have to show 4 circles over this spinning picture and a sequence of randomized letters in the center of the screen.

I've already tried several times to take a video of my ppt animation, but when executed by DirectRT v2010, it lags terribly.
So I've tried to build a chain of pictures of that background rotated of 1 degree each, and I've put them in fast sequence in the .csv file. It works fine for the first 10 pics. then it crashes, due to the high amount of memory needed I think.
Is there any easier way to make a pic spinning??

If you have any idea.. I'd really appreciate it!
Thanks in advance.