You'll find free tips, techniques, articles, and tutorials here, all designed to help you succeed when you present. This blog gives you knowledge. I'm passionate about turning Death by PowerPoint into Life by PowerPoint. 
If you don’t know or have other graphics software, you can use PowerPoint — and many people do. It’s not high end, but if your needs are simple, the fact that you know and have it is a great plus. PowerPoint 2007 improved the graphics engine and you can add many more effects, such as soft edges, beveled edges, and soft shadows.
You can insert photos (Insert> Picture> From File or Insert tab> Picture), then crop, resize, format, and move them. You can use AutoShapes/shapes as well.
When you have a look that you want, group everything. Go to the Drawing toolbar> Draw> Group. (In PowerPoint 2007, press Ctrl+G.)
Finally, right-click and choose Save as Picture. You can save in a variety of formats.
You can then use that image in another program, to upload to a Web site, or to reinsert into PowerPoint.
Here you see a Twitter background that I created in PowerPoint. Please follow me on Twitter for additional tips that I don’t publish on my site. Go to www.twitter.com/EFinkelstein.
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It’s interesting you suggest PowerPoint for this. I find many people try & do graphics in Word (which is a disaster) but PowerPoint offers better output options.
Robin, I agree that Word would be a disaster. PowerPoint is natively much more graphical.