Type "Derbiz removal" into google. Lot's of pages will be returned that can help you achieve this. Some seem more technical than others.
It seems DerBiz is a version of the "Elite Toolbar" so try downloading the removal tool here;
http://www.annoyances.org/exec/forum/winme/1119091621
Bare in mind that "DerBiz" is a "rogue-dialler" so every time you are connected to the internet you will be paying �1.50 per minute on your phone bill. Call BT 100 and get them to bar premium-rate numbers immediately.
As the poster in the above link suggests; download the removal tool on a friends computer and transfer it to your computer with a disc. Good luck.
Let us know how you get on.
H