You have given us many dump reports, they are mostly consistent. They indicate this driver to be the cause xbext xbext.sys Fri Oct 01 23:06:32 2010.
Several clues lead to the belief that this may be a serious virus.
No mention of the driver in Google
The relatively new date of the driver
The number of BSODs caused by this same driver
No mention in Google usually means that the virus changes names, possibly a rootkit.
My suggestion is that you post in the security section,, give the facts and wait for a security analyst to help you. I will, also, notify one for you.