My last so called period was on 1-4-08. It was light pink and then followed by brown spotting. It lasted for 3 days . It normally lasts for 5-7 days and it is very heavy. I'm very regular and my tubes have been tied for 5 years. Could I be pregnant? If so when should I take a test?

You are unlikely to be pregnant if your tubes have been tied. It may just be a light period.
Take a test to set your mind at rest.