Microsoft has just posted their security patch builletin for August. As usual all required patches for your PC can be found on Windows Update. Here"s a brief summary of the "critical" and "important" level vulnerabilities. (Read more for "moderate" level patches)
Update: Microsoft has just pulled several of the patch downloads from their site. Information pages seem to be up pending a re-release.
MS05-038: Cumulative Security Update for Internet Explorer (896727) Critical
Vulnerabilities exist in Internet Explorer, the most severe of these could allow an attacker to take complete control of an affected system.
A remote code execution vulnerability exists in Plug and Play (PnP) that could allow an attacker who successfully exploited this vulnerability to take complete control of the affected system.
MS05-043: Vulnerability in Print Spooler Service Could Allow Remote Code Execution (896423) Critical
A vulnerability exists in the Print Spooler service that could allow remote code execution.
MS05-040: Vulnerability in Telephony Service Could Allow Remote Code Execution (893756) Important
A vulnerability exits in the Telephony Application Programming Interface (TAPI) service that could allow remote code execution.