Acrobat tools
Acrobat Reader 5.1 does (at least in my PC version) have the capability of selecting and copying both text and graphics. The text copy tool icon looks like a capital "T" with a dotted line box next to it. The graphics copy tool looks like some small geometric shapes surrounded by a dotted line box. It's next to the text select tool.
If the original PDF document had the text scanned in as an image, not inserted as actual text, you can still copy it as a picture, but you won't have something you can edit.