Limited rights gigantically reduces the risk to get infected with malware.
Specially for DavidR here the Hall of Shame: http://www.threatcode.com/admin_rights.htm
Let it be a warning for those that do not believe in surfing with limited rights.
On XP also install SafeXP and use two accounts, one for things you doing with full rights, and one for your normal “ramblings” on the Internet,
It is surprising just how many programs require admin privileges, crazy.
Even those that don’t require it inherit your logon privileges, so if you have admin privileges your programs inherit this as does any malware gaining entry to your system via one of those programs. With admin privileges malware can reap havoc in your system, it may be a pain to logon as a limited user (especially where some of the Hall of Shame programs require admin privileges).
You can opt for the convenience of using an account with admin privileges, just use DropMyRights (see my signature) to lower the privileges for a specific program, namely those that access the internet, browsers, email, p2p, IM, etc.