What is it?
WSFTP Browser Plugin - wsbho2k0.dll

What does it do?
If you have an FTP program installed like WSFTP you will want to use that for all of your FTP transfers instead of the tool built into Internet Explorer. This Browser Help Object basically forces your FTP connections through WSFTP.

This is described as a BHO or Browser Help Object. If you're looking at your HJT log you will see a line that looks something like this:
O2 - BHO: Ipswitch.WsftpBrowserHelper - {601ED020-FB6C-11D3-87D8-0050DA59922B} - C:Program FilesWS_FTP Prowsbho2k0.dll

Virus Precautions:
You'll want to keep an eye on this google search for any known viruses. The normal location of this file is C:Program FilesWS_FTP Prowsbho2k0.dll