I missed the original when it was in the cinema and recorded it recently on tv. Watched it last night, as I thought it would be suitable Halloween fare. I really enjoyed it - a good, gory take on vampire mythos. Interesting and poignant twist near the end too. But I'm not sure it cried out for a sequel. Still, if I thought the sequel was anywhere near as good, I'd probably check it out. But the plot for the sequel sounds a bit derivative (John Carpenters Vampire$ anyone) and lacks the brilliant 'Vamps-in-a-town-that-has-no-sun-for-a-month' premise of the original).
As regards Melissa George's non-return, she's rightly getting great acclaim for her part in In Treatment and starred in the recent and well-received Triangle. She also had a recurring role in Grey's Anatomy and has a few current and future projects in her IMDB page. Hardly surprising she doesn't want to come back for a direct-to-DVD sequel.