Domain names are being snatched up faster than candy at the St. Patrick's Day parade. Heck, you don't even need a web page. Just get out there and register before you loose the opportunity to get the name you really want. Sometimes, it isn't a bad idea to register several similar domain names. You can register your full company name and a shorter, easier to remember version.
Some people even register common misspellings of their company's name.
Domain names can only use letters, numbers, and dashes. Spaces and symbols are not allowed. Also, domain names are not case sensitive. A name that may make perfect sense to you may be too hard for other people to remember. Recently, it was decided that other companies should be able to compete to sell domain names.