One very effective way to help prevent computer infections - particularly by trojan horses - is NOT to use an admin-level account for general browsing.
IMHO, ALL users should be simple "User" level, with an admin account available for "run as" and occasional logging in for admin tasks.
If a virus / malware piece of sh1t cannot write to the registry, install programs or whatever, then it is robbed of its ability to do harm.
SD