Adam Schwartz writes Top 10 Reasons To Use WordPress.org For Your Website in his blog. Here the list top ten reason to use WordPress for your web:
1. WordPress is Truly Free and Open Source
2. Automattic is an Awesome Company
3. Plugins Give You More Functionality
4. The Visual Editor and CMS are Outstanding
5. Easily Add a Blog To Your Site
6. Themes Let You Style Your Site
7. It’s Easy to Keep WordPress Secure
8. Google Loves WordPress
9. WordPress Sites are Accessible
10. Your Site Can Grow With You

Find more details about those reasons why he talk about it.

Theme default of WordPress have been changed. The new theme is Twenty Ten. This theme is very stylist. The header images of exactly 940 × 198 pixels will be used as-is. You can change the header image in any time. Thats available header option to do that. If you think the header theme is too height in size, you can modify and resize them via function.php.

Just change the size 198 in this function.php code:
define( 'HEADER_IMAGE_HEIGHT', apply_filters( 'twentyten_header_image_height', 198 ) );

After you change the height size, you must have an image header in the same size and upload it via header option (on your dashboard). Just the simple huh