Hello. I am about to embark on a one weel trip to Paris followed 2 weeks in a villa near Siena, Italy. I will be taking along my 41/2 year old and 18 month old daughters. Any ideas on activities, restaurants, day trips, anything? I need all the help I can get!

Obviously Italian beaches are great. And I know there are plenty of theme parks accross Europe. France has some pretty good ones. I don't know how it will be with such young'uns, so have a search on the web see if there's any arround France with special kids/toddler zones.
Good luck, I bet you the kids will appreciate all the stress you will embark upon. Although they probably will only thank you when they are a bit older.

Don't expect to do too much of the cultural stuff in Paris with the kids. I'd do a Bateaux-Mouche ride, or look into the BatoBus, which is a Seine-based water taxi. Champs de Mars around the Eiffel Tower has some fun kid stuff; also les Jardins Luxembourg. Just about every park area has a playground, too. You can do it!