http://mechbgon.com/srp/

Ruin a malware author’s whole day with a Software Restriction Policy! : )

If you’re using a Limited account on Windows XP Professional Edition, or a Standard user account on Windows Vista Business/Ultimate/Enterprise Editions, consider further enhancing your security by adding a Software Restriction Policy. Setting up a Software Restriction Policy takes just a few minutes, and it can be reversed if necessary. It’s a proactive
defense that won’t need updates or signatures to provide protection,
has no noticable performance impact, and protects your other layers of
defense from sabotage.

Notes:

Notes:

    *  you can’t use Software Restriction Policy if you have Windows XP Home, Windows Vista Home Basic, or Windows Vista Home Premium, but Limited or Standard accounts are still strongly suggested. Try them out; you can always go back if they don’t work well for your needs.
    *  I’ve added a couple of refinements in Step 5. One refinement is for Windows Vista. The other refinement is for 64-bit versions of Windows, which includes the 64-bit versions of Windows Vista, and also the rarely-used Windows XP Professional x64 Edition.
    *  If you’re an Information Technology professional, read Microsoft’s information on Software Restriction Policy http://technet.microsoft.com/en-us/windows/cc507878.aspx   for comprehensive information. The use of Software Restriction Policy that I’m showing on this page is just one possible implementation of it, most similar to what Microsoft calls a Line-of-Business PC setup.