An ex-manager of mine liked to say "Shy boys get nothing". If you don't ask, you don't get, and if you don't ask then you might spend your time at the new company kicking yourself for not asking.
Being a professional is all about getting paid what you think you're worth. The hiring company should deal with your request for a given salary in a professional manner - if they don't, then consider whether it's a place you want to work and consider how they're likely to deal with pay increases once you've started there.
Just be careful not to ask for a stupid amount of money, and remember that in this financial climate you're not likely to see anyone dishing out pots of gold. However, you might just get some other benefit (stock, one-off joining bonus) out of the discussion.
Good luck.