There is some advantage to running with a limited account.
However, it is difficult. Many popular pieces of software do not work
properly in this mode. Additionally, it isn't a panacea--it helps, but
considerable damage is still possible if a trojan or virus is executed.
I do have offices configured to run in limited user mode, where all the
users, in fact, know the administrative password, and use it, via Run As,
when neccessary. This works pretty well for a trusted group of employees.
So the answer is a no-brainer--limited is safer. The question is whether
the advantage is sufficient to justify the pain level in your particular
working environment. Try it out and see.