The logo and colors provide the face for your event and can help to build credibility. It is always a good idea to include your organization's logo on registration forms to lend the credibility of that entity to the event itself. However, creating a separate logo for the event itself can help you convey more ideas than your company logo can on its own.
Adding your company logo to your event marketing materials like flyers, emails, invitations, registration forms, and event websites is imperative, especially when your company or organization is an industry-wide expert or a household name. For example, Zig Ziglar conferences or Yahoo! Search Marketing seminars always rely on the brand recognition of the parent company to help create notoriety and credibility for their events. Using your organization's logo also helps to create consistency when you send registrants from your homepage to the registration form. Seeing a prominent reference to your parent organization reminds the registrant that the event is presented with the same quality and attention to detail that they have already experienced.
You should also consider creating a logo specifically for your event especially if the event has a large following and is building its own branding. It is not a bad idea to incorporate the general theme of your organization's logo into the event-specific logo, including the colors, shapes and fonts. However, make sure to give the event logo its own identity or twist which makes it unique from your primary logo. If you need inspiration for elements to add to the event logo you can take inspiration from the properties of the event itself. Consider the event venue (located in Florida? Consider adding a palm tree.), the type of event (what golf tournament logo is complete without a club, flag or ball?), and the industry. It may seem clich