Hi There Carlene!
Thanks for writing to me. Congratulations on starting to plan your first trip! Both of your prospective dates fall over holidays and school holiday breaks in 2010 (with the February trip on President's Day and the April trip over Easter.) The parks can be quite crowded during these times, with Easter being the more popular given the more moderate weather. Given that the crowds will be somewhat similar, I would base your choice on a number of other factors, including what type of weather your family prefers. April is lovely and warm, and February is obviously much cooler (can can get downright cold on some days.) I would also let your budget guide your choice, and check
www.disneyworld.com often for specials and promotions that may be available for your desired weeks
Regarding crowds, I tend to agree that Extra Magic Hours make the parks more crowded, however, they can be good way to see and do more at a given park for some families. Evening extra hours tend to start adding to the crowds in the early afternoon, so if you are planning on arriving early in the day and plan on leaving before the afternoon, you probably won't feel much impact. My kids are small and generally can't stay awake long enough to benefit from the evening hours, so we do tend to avoid parks with them on a given day. I find that the extra morning hours can be great if you have a family of early risers and can be at the gates a few minutes before the parks open. The crowds tend to build steadily, but by getting there early, you can enjoy reduced waits on many attractions.
Have a wonderful trip!
Tanya