The From address of an email can be whatever the sender of the email sets it to - so it entirely possible that the emails have nothing more do with you then being sent with your name written on them. If so, there is nothing you can do about it.
However, it sounds like people you know are getting these emails, which suggests they are being sent to addesses in your address book. That suggests some sort of malware infection.
Get some antivirus software and anti-malware software immediately and make sure your system is clean.
http://free.avg.com/
http://www.lavasoft.com/
Also be sure, assuming you use Windows, to visit http://update.microsoft.com/ with Internet Explorer and check that you have all the latest security fixes installed.