Spybot is NOT an antivirus, but an anti-spyware: another kind of pest.
Incredibar is not realy a virus but a foistware taking the form of a gaming toolbar.
As a spyware, it tracks your surfing habits and report what it find to it's maker, who, in turn, sell that information to advertisers. This mean that you get more targetted publicity and possibly more SPAM.
It also tend to hijack your start page and prefered search engine.
A foistware is any application bundled with another and set to be installed by default unless you specificaly deny that installation. It's a common dirty trick that some use to get some extra cash.
Check Add/remove programms for it. Uninstall it. OFFICIALY, it should be all you need to do to remove it from your system.
If that DON'T work:
In Internet Explorer, DISABLE ANY tool bar except for the basic ones. Normaly, you realy don't need most, even all, of the additional toolbars.
As it ALSO install itself in Firefox, and possibly also in Chrome or Opera, you must also disable it here.
In Spybot, set a boot time task to remove incredibar.
Restart is safe mode and launch a search for incredibar. DELETE any folder and file that comes up.
Get Ccleaner and use it to scan your system for remaining files and registry entries. A great, safe and free maintenance utility.
After this step, there should be no trace left of incredibar on your system.
Optional if you are brave:
Open the registry editor and search for "incredibar". If you get ANY hit in a "Run" key, delete the value. Also, DELETE any key and value referencing to incredibar. If a key contains several values, remove ONLY those refering to incredibar.