Won't be any issues at all. Dreamweaver doesn't require the cross program compatibility that Illustrator and Photoshop(or any of the other graphic editing programs) require. The only interaction the Dreamweaver and the other programs have is direct importing, which imports the completed file(image, flash, etc), not any raw files. I haven't ever ran different versions on the same machine, but here in the office we have different versions on different PC's with no issues(even PC to Mac doesn't cause any issues).