Learn to create interesting background in Illustrator.
Make a web document. Draw a rectangle with no stokes and just a fill.
Make a new gradient. I opened the Flowers swatches to pick the colours.
Drag the new gradient to the Swatches palette. Apply it on the rectangle.
Choose the Knife tool.
Create some cuts in the rectangle.
Choose everything and apply a 30 pixel feather.
Choose the bottom objects and apply the Tight Scribble Options.
Now you have a nice background for a Powerpoint presentation or any other use.