http://securityresponse.symantec.com/avcenter/FixSbigF.exe
This won't prevent additional instances of SoBig.F from infecting your computer. You will need to install an anti virus program if you haven't already. I recommend the Norton Anti Virus software because it scans incoming emails for virii and deletes/quarantines them as necessary.
Feel free to reply to this post if you require any assistance, or you can email me at chris@bj21.com.
Chris