What was the day of the week on 1 February 2004?

1 February 2004 was a Sunday.

2000 years give 0 odd days.

Years 2001 to 2003 are three ordinary years = 3 odd days.

Days to 1 February 2004 = 31 + 1 = 32, leaving 4 on division by 7.

Total odd days = 3 + 4 = 7, i.e. 0, which counts to Sunday.