A: 

I don't have Dreamweaver, but I suppose that its regex engine doesn't support lookaround - at least this introduction from Adobe doesn't mention it. So you'll need a workaround. One thing you could do (not pretty, but it works):

Use © $1QQQQ2009 as your replacement string, and then do a second pass, searching for QQQQ and replacing that with nothing. As long as you're sure that you don't have any real occurences of QQQQ in your text somewhere :)

Tim Pietzcker
A: 

If you don't capture the - as well as the whitespace before or after it and only capture the leading year, then it'll make life a bit easier: ©\s*(\d{4})\s*-\s*\d{3}[^9] then replace with: @ $1 - 2009

Just tried locally and it worked in the following test cases:

© 2002- 2008
© 2002-2005
© 2002- 2006
Danilo Celic