When is the election?
The first round, in which neither Sarkozy nor Royal will get the required 50% in a crowded field of candidates, will be on April 22.
After that, the top two (again, most likely Sarko and Sego) will likely go head to head in a second round, on May 6.
http://en.wikipedia.org/wiki/French_presidential_election%2C_2007
Calendar
February 22, 2007 - Publishing in the Journal officiel de la République française of the decree convocating the election[1]
March 16, 2007 - Deadline for sending the endorsements (500 required)
March 20, 2007 - Official candidate list announced
April 9, 2007 - Official campaign starts
April 20, 2007 - Official campaign ends
April 21, 2007 - First round of vote in Guadeloupe, Martinique, French Guiana, French Polynesia, Saint Pierre et Miquelon and in voting offices in embassies and consulates on the American continent
April 22, 2007 - First round of vote
April 25, 2007 - Official results announced winner might be announced
April 27, 2007 - Official candidate list for second round announced
May 5, 2007 - Second round of vote in Guadeloupe etc.
May 6, 2007 - Second round of vote
May 10, 2007 - Official results announced
May 17, 2007 - Expiration of the term of Jacques Chirac - latest possible date for handover