Unlimited account for Internet use

Hi,
I know that it is very wise to do your internet surfing on a limited account in Windows.
A thought I came up with was this - if you are in an administrator account in Windows XP Pro and then decide to 'switch user' instead of logging out and log onto a limited account; well if you are now surfing in your limited account is your pc still safe (seeing as the administrator account in loggon on but not being used).

Any suggestions?