Help!! Norton blocked something...am I infected???

Hi there,  I had this  notification from Norton pop up this morning. I had MSN Messanger open but was not downloading anything and not browsing any suspecious websites...

 

Category: Intrusion Prevention Date & Time,Risk,Activity,Status,Recommended Action

 

2012-07-29 8:44:34,High,An intrusion attempt by tonyboy.info was blocked

 

Status: Blocked

 

IPS Alert Name: Web Attack: Exploit Toolkit Website 8

Default Action: No Action Required

Action Taken : No Action Required

Attacking Computer: tonyboy.info (46.235.47.17, 80)

Attacker URL: tonyboy.info/56124560.html

Destination Address: 10.0.1.10, 49883

Source Address: 46.235.47.17 (46.235.47.17

Traffic Description : TCP, www-http"

 

 Network traffic from <b>tonyboy.info/56124560.html</b> matches the signature of a known attack.  The attack was resulted from \DEVICE\HARDDISKVOLUME2\PROGRAM FILES (X86)\WINDOWS LIVE\MESSENGER\MSNMSGR.EXE.  To stop being notified for this type of traffic, in the <b>Actions</b> panel, click <b>Stop Notifying Me</b>.

 

Does this mean that I am infected or did Norton do what it was suppose to do and block the attack from coming in???  I scanned with NIS full scan and Malwarebytes On-Demand and came up with nothing but tracking cookies that were deleted.....How can I be sure I am not infected with malware??? 

 

Thanks